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Friday, April 30, 2021

HLAA News: Join the Conversation about Walk4Hearing

HLAA News: Join the Conversation about Walk4Hearing

Link to Hearing Loss Association of America

Join the Conversation about Walk4Hearing

Posted: 30 Apr 2021 02:55 PM PDT

Want to find out how you can be part of this incredible community and show your support? This spring, Walk4Hearing is online and invites you to join from anywhere! If you haven't yet participated in...

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Thursday, April 29, 2021

Common sense that you must know when doing sheet metal processing

Common sense that you must know when doing sheet metal processingAfter the drawing is received, choose different blanking methods according to the different opening drawings and batches, including laser, CNC punching, shearing, molds, etc., and then make the corresponding opening according to the drawing. Place the worktable next to the CNC and the laser cutting, which is conducive to placing the sheet on the machine for processing and reducing the workload of lifting the board.

What are the steps involved in wonder metal sheet metal processing?

In the current production operations, what are the main steps of our more common wonder metal sheet metal processing technology? Perfect, the main steps of wonder metal sheet metal processing include: sheet metal processing drawing design, laser processing or (CNC stamping), bending, welding forming, electrostatic spraying or (liquid paint), and finally packaging and shipping.

HLAA News: New Legal Guidance and Resources to Ensure—and Expand—Access to COVID-19 Vaccines for People with Disabilities and Older Adults

HLAA News: New Legal Guidance and Resources to Ensure—and Expand—Access to COVID-19 Vaccines for People with Disabilities and Older Adults

Link to Hearing Loss Association of America

New Legal Guidance and Resources to Ensure—and Expand—Access to COVID-19 Vaccines for People with Disabilities and Older Adults

Posted: 29 Apr 2021 02:05 PM PDT

As part of a shared commitment to President Biden's National Strategy and Executive Order to ensure an equitable COVID-19 response, the Office for Civil Rights (OCR), the Administration for Community...

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Wednesday, April 28, 2021

How does the laser welding processing system change life?

Laser processing is one of the promising areas in laser applications. More than 20 laser processing technologies have been developed.

Laser cutting pipe processing is an important technology in laser processing. The quality of laser welding is directly related to the intelligence and accuracy of the welding system. A welding processing system must be able to produce welding products.

The laser welding system is generally composed of laser, optical system, laser processing machine tool, process parameter detection system, shielding gas transmission system, control detection system and so on. The core of the laser welding system is the laser.

Laser welding has the advantages of high precision, high efficiency, high strength, and good timeliness, ensuring quality, output and delivery time. At present, laser welding has become a competitive processing method in the processing industry. It is widely used in machinery, electronics, battery, aviation, instrument and other industries for spot welding, overlap welding and sealing welding of workpieces with special requirements.

brass machining requires that the laser has a high rated output power, a wide power adjustment range, a slow rise and slow fall of power, to ensure the quality of the beginning and end of the weld, and the work is stable and reliable. The lateral mode is a low-order mode or a fundamental mode. There are CO2 lasers, YAG lasers, LD pumped solid-state lasers, fiber lasers and semiconductor lasers. High-power semiconductor lasers are becoming more and more mature, and the commercial laser power has reached several kilowatts. The high-power semiconductor laser has uniform beam energy distribution, and the spot shape can be adjusted according to needs. The photoelectric conversion efficiency is high, the structure is compact, the weight is light, and the volume is small, which is convenient for field application. The disadvantage is that the beam quality is average and the divergence is high.

my country's cnc milling china technology is at the world's advanced level. It has the technology and ability of laser forming complex titanium alloy parts of more than 12 square meters, and has invested in the prototype and product manufacturing of many domestic aviation scientific research projects.

In October 2013, Chinese welding experts won the Brooke Prize, a high academic award in the field of welding, and the level of laser welding in China has been recognized by the world. At present, laser welding machine technology has been widely used in high-precision manufacturing fields such as automobiles, ships, airplanes, and high-speed railways, greatly improving people's quality of life, and leading the home appliance industry into the manufacturing era. Through home appliance technology, people will cherish and value science and technology more. Advanced laser technology can bring huge changes to people's lives.

Four advantages of laser pipe cutting machine

The utility model has the advantages of tube blank cutting, tube wall cutting, tube wall cutting and other tube cutting shapes. Commonly used are mechanical cutting, punching and advanced laser cutting. For small batches, mechanical cutting methods are mainly used, such as turning, milling, circular saw cutting, and grinding wheel cutting. The main problem is low production efficiency and large environmental pollution. As an advanced processing tool, laser cutting machine is gradually entering the pipe cutting market.

The tube laser cutting machine is mainly used for cutting various hollow tubes of non-metal solid materials, such as plastic tubes, PVC tubes, PVB tubes and other industrial and civil materials. This kind of pipe is generally used for home decoration, industry and water conservancy construction.

Four advantages of laser cutting pipe processing

Laser cutting technology is a technology with high production efficiency and high productivity. The laser pipe cutting machine has four advantages.

1. High cutting accuracy, high dimensional accuracy, smooth cutting, no burrs, and low material loss;

2. The heat-affected zone of laser cutting is very small, and there is almost no thermal deformation and oxidation. It can produce high-quality and more consistent parts, which is especially beneficial for subsequent automatic welding;

3. High cutting efficiency, mass production can be realized. All operations of laser cutting can be unified into the same unit as a continuous operation process, which greatly shortens the logistics time. The standard pipe length is 6 meters, and the traditional processing method requires very heavy clamping. Laser processing can easily complete the clamping and positioning of several meters of pipe, making batch processing possible.

4. cnc turning china machine is controlled by a digital system, which is also one of the advantages of the laser cutting machine for cutting pipes. First, it guarantees accuracy and flexibility. Laser tube cutting technology can process any programmed shape, and can cut in any direction. The shape of the template can be changed quickly without the help of any tools. Modify the design plan without affecting the entire production process; the greater advantage is that the end user can control the production of short or medium versions without making a large number of templates, which can respond to customer needs faster and achieve personalization custom made.

It can be seen that laser cutting pipes can replace mechanical drilling, milling, sawing, punching or cleaning burrs and other processing procedures that require different equipment and hard tools to realize the cutting, chamfering, beveling, or hole cutting of complex pipe structures. Processing of possible size and shape features such as notches. With the rapid growth of China's stainless steel pipe production and consumption, laser pipe cutting equipment is rapidly popularized in China, and the demand for cnc milling china talents and laser pipe cutting technology is also growing rapidly.

The knowledge that CNC engraving and machining must learn!

  COMPUTER NUMERICAL CONTROL engraving machine is good at fine machining of small tools, with the ability of milling, grinding, drilling and high-speed tapping. It is widely used in 3C industry, mold industry, medical industry and other fields. This article collects common questions about CNC engraving.

1 . What is the main difference between COMPUTER NUMERICAL CONTROL engraving and CNC milling?
Both CNC engraving and CNC milling use the principle of milling. The main difference lies in the diameter of the tool used. Among them, the commonly used tool diameter for cnc manufac turings is 6-40 mm, while the device diameter intended for CNC engraving is 0. 2-3 millimeter.
2 . Does CNC milling can only be used to get rough engineering and CNC engraving can only just be utilized pertaining to finishing?
Before answering this question, let us first understand the concept of the process. The rough machining process requires a large amount of machining, but the finishing machining amount is usually small , so some people habitually regard tough machining as "heavy cutting" and finishing as "light cutting". In fact, rough engineering, semi-finishing, and finishing are process concepts, which represent different processing stages. Therefore , the accurate answer to this kind of question is that CNC milling can be used for heavy cutting or light cutting, while COMPUTER NUMERICAL CONTROL engraving can only be used meant for light trimming.

  1. Can CNC decoration be utilized designed for rough machining of steel materials?
    To judge whether CNC engraving can process a certain material, it mainly depends on the size of the tool that can be used. The application used in COMPUTER NUMERICAL CONTROL engraving determines its maximum cutting capacity. If the mildew shape allows the use of tools with a diameter of more than 6 mm, it is strongly recommended to use CNC milling first, and then utilize the engraving method to remove the remaining material.
  2. Can the CNC machining center add a speed-increasing head to complete the decoration process?
    Can not finish this. This kind of product appeared at the exhibition 2 years ago, but it was unable to complete the engraving procedure. The main reason is that the design from the CNC machining middle takes into account its own range of equipment, and the overall structure is not suitable for engraving processing. The main reason for this wrong idea is that they mistakenly regarded the high-speed electric spindle as the only feature in the engraving machine.
  3. CNC machininged can use tools with a small diameter. Can it replace EDM?
    Cannot be replaced. Although decoration has narrowed the range of tool diameters for milling, small molds that could only be processed by EDM can now be processed by engraving. However , the length/diameter ratio of the decoration tool is generally around 5: 1 . When using small-diameter equipment, only very shallow cavities can be machined, and there is almost no cutting force in the EDM machining.. As long as the electrode could be manufactured, the cavity can be machined.
    six. What are the primary factors affecting engraving control?
    Machining is definitely a relatively complex process, and there are many factors that affect it, mainly including the following points: equipment tool characteristics, cutting tools, control systems, material features, processing technology, auxiliary fixtures and surrounding environment.
  4. What are the requirements for the control system of CNC turning?
    CNC engraving processing is milling processing first, so the control system must have the ability to control milling handling. For the processing of small equipment, the feedforward function must be provided at the same time to reduce the speed of the path in advance to lessen the breaking frequency of small tools. At the same time, it is necessary to increase the cutting speed in a comparatively smooth path section to improve the efficiency of engraving processing.
  5. What qualities of the materials will impact processing?
    The primary factors influencing the decoration performance with the material are the material type, hardness and toughness. The material category includes metallic materials and non-metallic materials. In general, the greater the hardness, the worse the processability, and the higher the viscosity, the worse the processability. The more impurities, the worse the processability, the greater the hardness of the particles inside the material, and the worse the processability. A general standard is: the higher the carbon content, the worse the workability, the bigger the alloy content, the worse the workability, the higher the content of non-metal elements, the better the workability ( however the nonmetal content in general materials is strictly controlled of).
  6. Which materials are ideal for engraving processing?
    nonmetallic materials suitable for engraving include organic glass, resin, wood, etc ., and nonmetallic materials that are not ideal for decoration include natural marble and glass. Metal materials suitable for engraving include copper, aluminum, and mild steel with a hardness less than HRC40. Metallic materials not ideal for engraving include quenched steel.
  7. What impact does the instrument itself have on digesting, and how?
    The tool elements that affect the engraving process include the software material, geometric parameters, and grinding technology. The program material found in the decoration process can be cemented carbide material, which is a powder alloy. The main performance index that determines the material performance is the average diameter of the powder. The smaller the diameter, the more wear-resistant the tool, and the bigger the durability of the tool. For more china turning knowledge, pay attention to the WeChat public account (CNC programming teaching) to receive the tutorial. The sharpness on the tool mainly affects the cutting force. The sharper the tool, the smaller the cutting pressure, the smoother the control, and the higher the surface quality, but the lower the durability of the device. Therefore , different sharpness should be selected when processing diverse materials. When processing relatively soft and sticky components, the slicing tool needs to be sharper. When the processing material is harder, the sharpness ought to be reduced to boost the durability of the cutting application. But it should not be too blunt, otherwise the cutting push will be too large, which will impact the processing. The key factor in the grinding of this tool may be the mesh number of the fine grinding wheel. A high-mesh grinding steering wheel can grind a more delicate cutting edge, which can effectively improve the durability of the tool. A high-mesh grinding wheel can grind a smoother flank surface and enhance the reducing surface top quality.
  8. What is the instrument life formula?
    Tool life is mainly the tool life in the finalizing of metal materials. The empirical formula is: (T is the software life, CT is the life parameter, VC may be the cutting linear speed, f is the amount of knife per revolution, and P may be the depth of your knife). Included in this, the lowering linear speed is the biggest influence on tool existence. In addition, program radial runout, tool milling quality, tool material and coating, and coolant will also affect device durability.
  9. How to protect the engraving machine application during handling?
    1) Protect the instrument setter from excessive oil erosion.
    2) Pay attention to the control of flying chips. Flying chips are very harmful to the machine tool. Flying into the electric control cabinet will cause a short circuit. Soaring in to the guide rail will reduce the life belonging to the lead screw and the guideline rail. Consequently , the device software must be The main part of the seal is well sealed.
    3) When moving the lamp, do not pull the light cap, it is easy to damage the lamp cap.
    4) During the machining method, usually do not observe near the lowering area to avoid flying chips to injure your eyes. When the spindle motor is certainly rotating, it really is forbidden to perform any operations on the work surface.
    5) When opening and closing the door of the machine program, do not open and close it violently. Through the finishing process, the shock and vibration during the door opening process may cause the machined surface to have knife marks.
    6) The spindle velocity should be set, and start processing. Otherwise, because the spindle starts to rotate slowly, it will start producing without reaching the desired rate, causing the motor to suffocate.
    7) It really is forbidden to place any tools or perhaps workpieces on the beam of the device tool.
    8) It is strictly unacceptable to put magnetic tools such as magnetic suction cups and dial indicator holders on the electric powered control cupboard, otherwise the display will be damaged.
  10. There is a phenomenon of holding back through the processing of a new device, and the processing is very laborious. What parameters need to be adjusted at this time?
    The reason why the machining is very laborious is that the power and torque of the spindle cannot withstand the current clipping amount. A reasonable approach is to remake the road to reduce the depth within the tool, the depth for the groove, and the amount of trimming. If the entire processing time is significantly less than 30 minutes, you can also adjust the cutting acceleration to improve the cutting state.
  11. What's the role of cutting fluid?
    Focus on cooling oil for metal processing. The role of the cooling system is to take away the trimming heat and flying potato chips, and play a role in lubricating the refinement. The coolant will take away the cutting heat, reduce the heat transferred to the tool and the motor, and increase their service life. Take away soaring chips in order to avoid secondary cutting. Lubrication can easily decrease the slicing force and make the developing more stable. In the copper processing, the selection of oil-based reducing fluid can certainly improve the surface quality.
  12. What are the stages of tool wear?
    Tool wear is divided into three stages: initial wear, normal put on, and sharp wear. In the initial stage of use, the main cause of tool put on is that the temperature of the tool is low, and the optimal cutting temperature is not reached. At this time, the wear from the tool is mainly abrasive have on. Such don has a greater impact on the tool. More knowledge of COMPUTER NUMERICAL CONTROL programming Pay attention to the WeChat public account (edm engineering teaching) to get the tutorial, you can easily cause the application to collapse. This stage is a very dangerous level. If it is not really handled well, it may directly cause the tool to collapse and fail. When the tool passes the original wear period, the lowering temperature in the tool reaches a particular value. This is the primary wear is diffusion dress in, and its function is principally to cause local spalling. Therefore , the use is smaller and slower. When the dress yourself in reaches a certain level, the tool fails and enters a period of rapid be dressed in.
  13. Why do tools have to be run-in and how to run-in?
    We mentioned above that the tool is easy to collapse in the initial put on stage. In order to avoid the phenomenon of instrument collapse, we must run-in the tool. The cutting heat of the instrument is gradually increased to a reasonable temperature. It really is verified simply by experiments the same refinement parameters are used for comparison. It can be seen that after running-in, the tool lifestyle has increased by simply more than 2 times.
    The method of running-in is usually to lessen the feed rate by half while maintaining an acceptable spindle swiftness, and the developing time is about 5-10 minutes. Take a small value once processing soft materials, and take a large value when ever processing hard metals.
  14. How exactly to judge the severe wear with the tool?
    The technique of judging severe software wear is definitely:
    1) Once listening to the processed sound, there is a harsh call;
    2) Listening to the sound of the main shaft, the primary shaft is obviously holding back;
    3) It feels that the vibration increases during processing, and the machine program spindle appears obvious vibration;
    4) Looking at the application effect, the knives around the processed bottom surface are sometimes good and sometimes bad ( if it is like this at the beginning, it means the fact that depth on the knife is too deep).
  15. When should I change the tool?
    We should change the tool at about 2/3 of this tool your life limit. For example, the tool is severely worn in 60 minutes, the next time you process, you should begin the device change in 40 minutes, and develop the habit of changing the application regularly.
  16. Can seriously worn equipment continue to be processed?
    After the device is significantly worn, the cutting power could be increased to 3 times the normal. The cutting drive has a great influence within the service life of your spindle electrode. The lifespan of the spindle motor as well as the force will be inversely proportional to the third power.

    For instance, when the trimming force can be increased by three times, application for 10 minutes is equivalent to the spindle using 10*33=270 minutes under normal conditions.
  17. How to determine the protruding length of the tool during roughing?
    The protruding amount of the tool is as short as possible. However , in actual processing, if it's too short, the length of the instrument must be modified frequently, that may affect the absorbing efficiency too much. So how should the protruding length of the program be controlled in real processing? The principle is as follows: a φ3 size cutter bar can be prepared normally if it protrudes 5mm. The φ4 diameter instrument bar could be processed normally if it protrudes 7mm. The φ6 dimension tool club can be highly processed normally if this protrudes 10mm. Try to go below these values the moment loading the knife. If the space of the upper knife is certainly greater than the above value, try to control the depth belonging to the machining when the tool is normally worn. This is a bit difficult to grasp and requires more exercise.
  18. What must i do if the software breaks suddenly during taking?
    1) Stop processing and check the existing serial quantity of processing.
    2) Check whether there is a broken knife body at the broken knife, and take it out if there is one.
    3) Analyze the reasons just for tool breakage. This is actually the most important thing. is the program broken? If we want to analyze, we should evaluate the various factors that affect the processing mentioned previously. But the reason for the broken tool is that the force for the tool all of a sudden increases. Or the path problem, or the programme jitter is too big, or the material has lumps, or maybe the spindle motor speed is incorrect.
    4) After analysis, change the tool for dealing. If the path is not changed, the original serial number should be advanced one serial number for accomplishment. At the moment, you must focus on lower the feed rate. One is because the broken application is hardened severely, plus the other is the tool running-in.

Tuesday, April 27, 2021

Hall Sensor

The Hall effect is the working principle of the Hall sensor. It is a kind of electromagnetic effect, in which an orthogonal current and magnetic field are applied to the Semiconductor. The carriers in the Semiconductor are subjected to the Lorentz force and deflected. In different directions Gathering, thereby generating an electric field. There is a built-in voltage, this voltage is the Hall voltage, the greater the magnetic field strength, the greater the Hall voltage.

Hall Sensor
Hall sensor

The working principle of the linear Hall sensor, the output of the linear Hall sensor is an electrical signal proportional to the measured magnetic field strength. For example, the linear Hall sensor 3503 has three pins which are positive VS, V out and GND. Among them The positive VS is connected to a power supply of 4.5 to 6V. Power is supplied to the 3503, and the GND is grounded. The shell of the 3503 can induce the magnetic field, and implements the magnetic field strength in the form of voltage output at the pin of V out. The next output diagram shows that the 3503 is good When the magnetic field strength is 0 Gauss, V out is equal to 2.5V. When the magnetic field strength changes by 1 Gauss, the output changes about 1.3 millivolts.
When the 3503 sensor measures the magnetic field, it needs to pass the magnetic field lines through its effective sensing element to be detected. The magnetic field lines pass through the Hall sensor. The stronger the magnetic field, the more magnetic field lines pass through the Hall sensor, and the weaker the magnetic field passes through. The fewer lines of magnetic force, the Hall sensor outputs a corresponding signal to indicate the strength of the magnetic field according to the number of magnetic lines that pass through.

HLAA News: Emergency Broadband Benefit Webinar for Consumers and Outreach Partners

HLAA News: Emergency Broadband Benefit Webinar for Consumers and Outreach Partners

Link to Hearing Loss Association of America

Emergency Broadband Benefit Webinar for Consumers and Outreach Partners

Posted: 27 Apr 2021 03:05 AM PDT

On Tuesday, April 27, 2021, starting at 3:00 p.m. ET, the Federal Communications Commission (FCC) will host a public webinar to provide information on the Emergency Broadband Benefit (EBB). EBB is a...

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Friday, April 23, 2021

What should I carry out if clear plastic injection molding is unfinished?

   This is a frequently encountered problem, but it is also relatively easy to solve. When it is really not solved by technological means, it can be improved from the design and manufacture of molds, which can generally be solved.

What should I perform if plastic material injection molding is imperfect?

This is a frequently encountered problem, but it is also relatively easy to solve. When it is really not solved by technological means, it can be improved from the design and manufacture of molds, which can generally be solved.

1 . Equipment:

(1) The capacity of the injection molding machine is small. When the quality from the product exceeds the actual maximum injection quality of the injection molding machine, it is obvious that the amount of material supplied will not make ends meet. If the top quality of the product is close to the actual injection quality of the shot molding equipment, there is a problem of insufficient plasticization. The heating time of the material in the barrel is usually insufficient. As a result, the appropriate melt cannot be provided to the Cnc Machining mold in time. In this case, the problem can only become solved by replacing the injection molding machine with a large capacity. Some plastics such as nylon (especially synthetic 66) have a narrow melting range and a large specific heat. An injection molding machine having a large plasticizing capacity is required to ensure the supply of materials.

(2) The temperature displayed by the thermometer is not true, the bright high is definitely low, and the material temperature is too low. This is because the temperature control device such as thermocouple and its wiring or the temperature difference millivoltmeter fails, or because the heating coil far away from the heat measurement point is aging or burned, heating failure has not been found or has not been repaired and replaced with time.

(3) The diameter in the inner hole of the cnc turning nozzle is too large or perhaps too small. If it is too small , due to the small flow diameter, the specific volume of the strip will increase, which will easily be cooled, block the feed channel or consume the injections pressure; The condition of low force. At the same time, plastic materials such as uhmw machining cannot reduce the viscosity because of the lack of large shear warmth, which makes it difficult to fill the mold.

The nozzle can be not well matched with the inlet of the main runner, as well as the overflow with the mold plus the filling on the mold are often unsatisfactory. The nozzle itself has high flow resistance or is blocked by foreign matter, plastic carbonized deposits, etc .; the spherical surface of the nozzle or the primary runner inlet is damaged or deformed, which affects the good cooperation with the other party; edm Machining faults or deviations cause the nozzle and the main runner axis to have an inclination displacement or the axial pressing surface area to separate; the nozzle ball diameter is certainly larger than the main runner entrance ball diameter, due to the gap at the edge, the nozzle axis gradually increases under the squeeze of this overflow The pushing pressure will cause the plastic gear to be dissatisfied.

(4) The plastic material frit blocks the feeding channel. Because the plastic is normally partially melted and agglomerated in the hopper dryer, or the temperature inside the feed section of the barrel is too high, or the plastic grade is going to be not selected properly, or maybe the plastic contains too much lubricant, the clear plastic will enter the feed port or screw at the reduced diameter position. Premature melting in the deep groove of your screw end, dog-supplier the pellets and the melt are bonded to each other to form a "bridge", which blocks the channel or envelops the screw, and slides circularly with the mess rotation, and cannot move forward, causing interruption of feeding or irregular fluctuations. This situation can only end up being fundamentally resolved after the passage is cut through as well as the material blocks are eliminated.

(5) The nozzle cold material enters the mold. Injection molding machines usually only install straight-through nozzles due to pressure loss. However , if the temp of the front end of the barrel and the nozzle is too large, or there is too much material at the front end of the barrel or clip under high pressure, "salivation" will occur, which will cause the vinyl to accidentally enter the key runner entry before the injection is started and the plastic mold is open. And it becomes hard underneath the cooling effect of the template, which usually prevents the melt from entering the cavity smoothly. At this time, the temperature belonging to the front end within the barrel plus the nozzle should be lowered, the storage capacity for the barrel must be reduced, and the back pressure ought to be reduced to avoid excessive dissolve density at the front end of the barrel.

(6) The treatment cycle is actually short. Due to the short cycle, the material heat is too late to keep up, which will also cause material shortage, especially when the voltage fluctuates greatly. The period should be adjusted accordingly according to the supply voltage. Die Casting Tooling Generally, the injection and holding pressure time are not considered during the adjustment. The main consideration is to adjust the time from the completion of the holding pressure to the return from the screw, which in turn does not affect the filling and molding conditions, and can extend or shorten the preheating time of the pellets in the barrel.

What should I perform if plastic material injection molding is imperfect

2 . Mould:

(1) The mildew casting system is defective. The flow channel is too small , too thin or perhaps too long, which will increases fluid resistance. The primary runner should increase the size, and the athlete and branch runner needs to be round. The runner and also the mouth is too large, as well as the injection force is inadequate; the jogger and gate are clogged by impurities, foreign matter or carbide; the runner and door are rough with scars, or have sharp angles, plus the surface roughness is poor, which impacts the material circulation;

The athlete does not have a cold slug well or the chilly slug well is too small , and the opening direction is without question wrong; for multi-cavity molds, the jogger and gate size distribution should be carefully arranged, otherwise there will be only the main runner or the thick and short gate. The situation where the cavity can be filled but other cavities cannot be filled. The diameter in the runner need to be increased appropriately to reduce the pressure drop of the burn flowing towards the end with the runner, and the gate on the cavity farther from the main runner should be enlarged to make the injection pressure and materials flow velocity of each tooth cavity basically the same.High Pressure Die Casting & Tooling Services | China Top Die Casting Companies | MINGHE

(2) The mold design is unreasonable. The mold is too complex, with many turns, improper selection of the feed inlet, too narrow runner, limited number of gates or improper form; the partial portion of the product is very thin, the thickness of this entire product or part should be increased, or an auxiliary must be set near the insufficient filling Runner or gate;

It is not uncommon intended for inadequate venting measures inside the cavity to cause dissatisfaction with the parts. This defect mostly occurs in the corners of the item, deep recesses, thin-walled parts surrounded by thick-walled parts, and thin-walled parts formed simply by side entrance. The bottom of your bottom shell, etc .How to use the CNC wire cutting machine reasonably?

The design to eliminate this defect includes opening effective vents, selecting a reasonable door position to help make the air easy to discharge in advance, and when necessary, deliberately making a certain part of the trapped area of the cavity into an insert to make the air escape from your insert. Gap overflow; to get multi-cavity forms that are prone to unbalanced gateway distribution, the number of injection cavities should be decreased if necessary to ensure that other cavity parts are qualified.

3. Process:

(1) Improper give food to adjustment, lack of material or perhaps excessive material. Inaccurate nourishing metering or abnormal feeding control system operation, abnormal injection routine caused by hypodermic injection molding machine or form or operating conditions, low pre-plastic back pressure, or low particle density in the clip or barrel may cause materials shortage. For large particles, Pellets with many voids and plastics with large crystalline specific volume changes, Shalashala Laser Cutting Machine Blogsuch as polyethylene, polypropylene, nylon, etc ., as well as materials with higher viscosity, including ABS, ought to be adjusted to a higher volume. If the temperature belonging to the material is undoubtedly high, the volume should be modified.

When there is certainly too much material at the end within the barrel, the screw will certainly consume extra injection pressure to compress and push the excess stock in the gun barrel during injection, which greatly reduces the effective shot pressure for the plastic entering the mould cavity. The product is hard to fill.

(2) The injections pressure is actually low, the injection time is brief, and the plunger or twist returns too early. Molten plastic has larger viscosity and poor fluidity at lower working temperatures, so it needs to be injected at higher pressure and speed. For example , in the production of ABS color parts, the high temperature resistance of the colorant limits the heating heat range of the barrel, which has to become compensated by simply higher treatment pressure and longer hypodermic injection time than usual.

(3) The injection speed is slow. The injection speed is of great significance for some products with complicated shapes, huge thickness changes, and long processes, as well as plastics with high viscosity, such as toughened ABS. When the product can not be filled with ruthless, high-speed shot of ptj machining parts should be considered to overcome the problem of filling discontentment.

(4) The material temperature is too low. The temperature of the front end from the barrel is low, as well as the viscosity in the molten materials entering the cavity rises too early to the point where it is difficult to flow as a result of cooling a result of the shape, which hinders the filling of the far end; the rear part of the barrel or clip is a plastic with low temperature and substantial viscosity Difficult flow slows the forward movement with the tsmachining screw. As a result, it seems that the pressure displayed by the pressure gauge is sufficient, but the melt actually enters the cavity in low pressure and low speed;

If the nozzle temp is low, it may be that the nozzle is in contact with the cold black mold for a long time throughout the fixed feeding and loses heat, or perhaps the nozzle heating system ring is usually insufficiently heated or has poor contact, resulting in cold, frigidity, frigidness, coldness of the material, which may block the feeding channel on the mold; if the mold does not have cool material Well, with self-locking nozzles and post-feeding procedures, the valve can maintain the necessary temps; the nozzle is too frosty when it is just turned on, and sometimes a flame gun can be used for external heating to accelerate the temperature of this

Four, raw materials:

Plastic has poor fluidity. Plastic Machining Service often uses recycled components, and recycled materials often reflect a tendency to increase viscosity. The experiment pointed out that the unit volume denseness of molecular chain scission generated by oxidative cracking increased, which increased the viscosity of your flow in the barrel and cavity, plus the regenerated scraps promoted the production of more gaseous substances, which caused the injections pressure to get lost. Increased, causing difficulty in filling the mold.

In order to improve the fluidity of the plastic material, it should be considered to add exterior lubricants just like stearic acid or its salts, preferably silicone oil (viscosity 300~600cm2/s). The addition of lubricants not only improves the fluidity of the clear plastic, but also improves the stability and reduces the air level of resistance of gaseous substances.

Thursday, April 22, 2021

What is the principle of a power transmitter?

The power transmitter is a combination of multiple precision parts and requires careful use and maintenance. Before using a power transmitter, you need to know its principle.

What is the principle of a power transmitter? Introduction to the principle and characteristics of power transmitters

Principle of power transmitter


The power transmitter is mainly composed of three-phase isolated sampling circuit, A/D converter, single chip microcomputer, DSP device, D/A converter, calibration amplifier and special thick film integrated V/I converter.

After the three-phase AC input signal passes through the three-phase isolation sampling circuit, the common ground tracking voltage signal of the three-phase current and the three-phase voltage signal is formed. Under the control of the single-chip microcomputer, the A/D converter performs multi-point synchronous sampling on it, and the sample is obtained The data is calculated by the DSP device according to the principle of electrical engineering to calculate the three-phase active power (digital quantity) of the measured signal, and then the digital signal representing the three-phase power is converted into an analog quantity by the D/A converter, which is amplified and calibrated by the calibration amplifier Then, a direct current voltage output VZ is formed; the VZ output is passed through a dedicated thick film integrated V/I converter to form a 0-20mA or 4-20mA direct current output IZ.

Performance characteristics of power transmitter

As a professional instrument salesperson, you must be familiar with the characteristics of power transmitters and be more professional when communicating with customers.

The three ports of analog output, input, output, and power supply are isolated from each other.

Good linearity and high precision.

Automatic zero calibration and excellent temperature characteristics ensure the long-term stability of the instrument and avoid the need for periodic calibration of the transmitter.

All parameters are digitally calibrated. The analog adjustment of the conventional potentiometer is abandoned, the hardware circuit is simplified, and the reliability and stability of the whole machine are improved.

Perfect electromagnetic compatibility design, with strong anti-electromagnetic interference ability.

Full use of SMT devices, so that the product has the advantages of small size, low power consumption, and light weight.

Digital output

The input is isolated from the power supply and the output. For power transmitters using optical fiber transmission, the optical fiber not only plays a transmission role, but also plays a role in isolation. It can completely avoid the loss and interference of the transmission link, and is suitable for high-precision measurement in various complex electromagnetic environments;

The digital output transmitter is convenient for networked and intelligent applications.

The digital output power transmitter can form a virtual instrument together with the transmission system and the host computer. The function and display mode of the virtual instrument are determined by the software, which can realize multi-parameter values, meters, real-time waveforms, trend curves, and bar graphs. , Pie chart, vector diagram and so on.

HLAA News: HLAA Receives Permission from the FDA to Host a Meeting on Sensorineural Hearing Loss on May 25

HLAA News: HLAA Receives Permission from the FDA to Host a Meeting on Sensorineural Hearing Loss on May 25

Link to Hearing Loss Association of America

HLAA Receives Permission from the FDA to Host a Meeting on Sensorineural Hearing Loss on May 25

Posted: 22 Apr 2021 11:16 AM PDT

HLAA has received permission from the U.S. Food and Drug Administration (FDA) to host an Externally-Led Patient-Focused Drug Development Meeting (EL-PFDD) for People and Families Living with...

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Wednesday, April 21, 2021

How to set the low pressure and high pressure clamping positions?

The clamping process is generally divided into three or four stages, generally fast-slow-high pressure; fast clamping, according to the structure of the mold, sees it as a flat plate, or a slider, and different molds are set first The pressure/speed/position during rapid mold clamping, without affecting the efficiency, set the appropriate pressure/speed/position. Pay attention to not only make the mold smooth, but also reflect the principle of rapid mold clamping.

Low pressure-slow speed; this Precision Cnc Machining Metal Parts is the most important & in the jog state, set the pressure to 0, slow down the speed, and set the position to 0, because the machine itself has a bottom pressure, although the pressure is 0, cnc parts The mold will still be closed. After the mold is closed, because the position is 0, the high pressure cannot be raised. At this time, the low pressure position is changed to the value displayed on the panel according to the position of the mold base displayed on the main panel;

High pressure; Generally speaking, it is necessary to set the high pressure of the mold clamping according to the projected area of ​​the product and the performance of the material. After setting the appropriate value, you need to adjust the low pressure protection again, press the previous step to re-correct the position of the low pressure mold. The guarantee is indeed valid.

1. Under the premise of ensuring the mold clamping speed, the low pressure mold clamping pressure should be set as low as possible, as long as precision turning can reliably offset the friction resistance of the mold clamping (the friction resistance between the template and the large pillar, the guide pillar after the movable mold contacts The friction resistance of the guide sleeve, the friction resistance of the inclined guide post slider, and the friction resistance of the movable template and the supporting parts, etc.).

2. It is necessary to set a sufficient low-pressure protection stroke (should be larger than the size of the product, or larger than the size of the gripper of the manipulator if there is a manipulator), too large a low-pressure protection stroke will affect the accurate setting of the low-pressure protection pressure and low-pressure protection time, so the setting should be reasonable .

3. After calculating the actual time when CNC Drilling Services low-voltage protection starts and ends, the low-voltage time is set to be slightly greater than the actual time (the margin is less than 1 second to ensure that the mold clamping action signal output is stopped in time when there is a foreign body). The principle of low-voltage protection is In a certain low-voltage time, the computer cannot sample the high-voltage signal, and the computer determines that there is a foreign body in the mold cavity. At this time, the computer should in principle stop the mold-clamping signal output, and simultaneously alarm and output the mold-opening signal.

4. Set the required clamping force first and then set the clamping high pressure according to the proportion. The pressure of the machine system with different clamping forces is the same. Using this mechanism, the clamping force can be accurately preset by setting the CNC Lathing high pressure pressure.

5. Set the high-pressure stroke position to be too large first. At this time, gradually reduce the high-pressure stroke position according to experience. When the high-pressure stroke cannot be raised or the machine hinge cannot be straightened, then slightly adjust the high-pressure stroke to make the clamping force reliable.
If there is a slider, the protection position must be greater than the height of the slider guide post, and the pressure should be as small as possible.

There is an inspection standard for low-pressure mold protection. Put a 0.5-2mm thick cardboard. If the mold cannot be closed, it proves that you have set up successfully!

Analysis of several important injection molding process parameters

                                            The effect of plastic viscosity and conditions on viscosity
The nature of the friction between macromolecules when the molten plastic flows is called the viscosity of the plastic. The coefficient of this viscosity is called the viscosity, so the viscosity is a reflection of the fluidity of the molten plastic. The greater the viscosity, the stronger the viscosity of the melt. , The worse the fluidity, the more difficult the processing.
In industrial applications, comparing the fluidity of a plastic is not by its viscosity value, but by its melt flow index (called MFI): the so-called MFI means that the melt is subjected to a rated pressure at a certain melting temperature. , The weight of the melt that passes through the standard die in a unit time (usually 10 minutes). Expressed in g/10min, such as injection molding grade PP materials, different grades, the value of MFI can vary from 2.5 to 30, and the viscosity of plastics is not Unchanging, changes in the characteristics of the plastic itself, the influence of external temperature, pressure and other conditions can all contribute to the change in viscosity.

1.1 The influence of molecular weight

The larger the molecular weight, the narrower the molecular weight distribution, and the greater the viscosity reflected.

1.2 The impact of low-molecular-weight additives

The addition of low molecules can reduce the force between the macromolecules. Therefore, the viscosity is reduced. Some plastic molding time is added with solvents or plasticizers to reduce the viscosity and make it easy to mold.

1.3 The influence of temperature viscosity

Temperature has a great influence on the viscosity of most molten plastics. Generally, the higher the temperature, the lower the reflected viscosity, but the magnitude of the decrease in the viscosity of various plastic melts is different:

PE/PP/uhmw machining, increasing the temperature has little effect on improving fluidity and reducing melt viscosity. If the temperature is too high, the consumption will increase, but the gain is not worth the loss.

For PMMA/PC/PA and other plastics, the viscosity will decrease significantly when the temperature rises, and the increase in the temperature of PS ABS also has great benefits for reducing the viscosity and molding.

1.4 The influence of shear rate

Effectively increasing the shear speed of the plastic can reduce the viscosity of the plastic, but there are exceptions to some plastics, such as PC, whose viscosity is hardly affected by the screw speed.

1.5 The impact of stress

The effect of pressure on viscosity is more complicated. Generally, the viscosity of PP&PE is not greatly affected by pressure, but the effect on PS is quite significant. In actual production, on machines with better equipment, attention should be paid to high-speed injection, that is, high shear. The effect of cutting speed should not blindly increase the pressure.

                      The influence of the control of the injection temperature on the molding process

The so-called barrel temperature control refers to how the plastic is uniformly heated from the raw material particles into the plastic viscous fluid in the barrel, that is, how to configure the barrel baking temperature.

2.1. The adjustment of the barrel temperature should ensure that the machining uhmw plastic is well plasticized, and can be injected and filled smoothly without causing decomposition.

This requires us not to consciously lower the plasticizing temperature due to the sensitivity of the plastic to temperature, and use injection pressure or injection speed to forcibly fill the mold.

2.2.The melting temperature of plastics mainly affects the processing performance, but also affects the surface quality and color.

2.3. The control of the material temperature is related to the part mold. For large and simple parts, the weight of the part is close to the injection volume, and a higher baking temperature and thin wall are required. High baking temperature should also be used for complex shapes. On the contrary, for thick-walled parts, some additional operations, such as inserts, can be used at a low baking temperature, to identify whether the temperature of the plastic melt is appropriate, you can use the inching action to observe the air injection at low pressure and speed, and it is suitable The temperature of the material should be such that the sprayed material is strong and strong, does not contain bubbles, does not curl, and is bright and continuous.

2.4. The configuration of the material temperature is generally increased from the feeding section to the discharging section in order, but in order to prevent the overripe decomposition of the plastic and the change of the color of the part, it can also be slightly lower than the middle section. The improper configuration of the material temperature may sometimes cause the screw to be stuck. Fault-the screw does not rotate or runs idly, which may also be caused by the excessive injection pressure or the failure of the screw check ring (meson), which caused the thin melt at the front of the barrel to flow back in the direction of the feed zone.

When these backflowing materials are poured into the tiny gap between the threaded end surface and the inner wall of the barrel and are cooled at a lower temperature, the cold solidified into a layer of film is tightly clamped between the two walls, so that the screw cannot rotate or slip. Affect feeding.

At this time, do not forcibly loosen or inject. It is recommended that the cooling water at the feeding port be temporarily closed, and the temperature of the feeding section is increased to 30-50 degrees Celsius higher than the melting point of the plastic, and the temperature of the discharging section is reduced to near the melting temperature at the same time, and wait for 10 After ~20 minutes, turn the screw carefully, restart it when it can turn, and then slowly add the material.

Pressure control during the injection cycle

3.1. The actual applied pressure should be higher than the pressure of the full cavity. When plastic machining, the mold control pressure rises sharply, and finally reaches a peak. This peak is usually called the injection pressure. The injection pressure is obviously higher than the full cavity pressure. On the high side.

3.2. The role of pressure holding pressure: After the mold cavity is filled with plastic until the gate is completely cooled and closed for a period of time, the plastic in the mold cavity still needs a relatively high pressure support, that is, pressure holding. Its specific functions are:

A: Supplement the amount of material close to the gate, and prevent the unhardened plastic in the cavity from flowing back to the source of the gate under the action of residual pressure before the gate is condensed and closed.

B: Prevent shrinkage of parts and reduce vacuum bubbles.

C: Reduce the phenomenon of sticking mold bursting or bending deformation due to excessive injection pressure of the part. Therefore, the holding pressure is usually 50% to 60% of the injection pressure. If the holding pressure or the time is too long, it may be The cold material on the gate and runner is extruded into the parts, so that the cold material is added to the position near the gate, and the cycle is extended without any benefit.

3.3. Selection of injection pressure

A. Choose according to the shape and thickness of the part. B. Choose according to different plastic materials.

When the production conditions and product quality standards permit, it is recommended to adopt the process conditions of low temperature and low pressure.

3.4. Adjustment of back pressure

The back pressure represents the pressure experienced by the plastic plasticizing process. Youjin is also called plasticizing pressure.

A. The color mixing effect is affected by the back pressure, the back pressure increases, and the mixing effect is strengthened.

B. Back pressure helps to eliminate various gases from plastic parts and reduce silver streaks and bubbles.

C. Proper back pressure can avoid local stagnation in the barrel, so the back pressure is often increased when cleaning the barrel.

3.5 Control of injection speed

The effect of speed: the advantage of low-speed filling is that the flow rate is stable, the size of the part is relatively stable, the fluctuation is small, the internal stress of the part is low, and the internal and external stress consistency is better. The disadvantage is that the part is prone to delamination and poor melting point. Low injection pressure can be used for high-speed filling, which can improve the gloss and smoothness of the product, eliminate the phenomenon of seam lines and delamination, reduce shrinkage and depression, and make the color more uniform.

The disadvantage is that it is easy to produce "free jet", that is, stagnation or eddy current. Excessive temperature rise, yellow color, poor exhaust and sometimes difficult demolding. Plastics with high viscosity may cause melt fracture and fog on the surface of the part. At the same time, it also increases the tendency of wing curvature and thick parts to crack along the seam line caused by internal stress.

Next Generation of IGBT

Efficient Chips and the Thermal Cycle Failure Free SLC-package-technology
This concept is convincing because it is based on a standardized package outline while also capable of delivering the highest power density, scalability by easy paralleling, low stray inductance, capability to operate with fast switching devices like SiC MOSFETs and having excellent current sharing balance. In combination with the latest 7th generation IGBT and Diode efficient chips and the thermal cycle failure free SLC-package-technology, the LV100 module provide the best overall performance. In the 1700V, a current rating of 1200A has been realized which represents an outstanding current density considering the compact package footprint of only 144x100mm².

NEXt Genaration IGBT
NEXt Genaration IGBT

LV100 Internal Layout
In high power IGBT modules, multiple chips are connected in a parallel configuration because IGBT chips sizes are limited and usually the rating maximum current is in a range of ~200A for IGBT chips with blocking voltages of 1200V or 1700V.

Achieving Homogeneous Loss and Heat Distribution
Therefore, for the realization of an IGBT module with a current rating of 1200A or more, paralleling of at least six or more IGBT chips is required. While designing the layout, the current balancing between the chips connected in parallel has to be considered. Equally shared chip currents are required for achieving homogeneous loss and heat distribution. A non-homogeneous current distribution causes a certain chip to carry the highest current and this chip will experience the highest temperature which ultimately limits the performance and life-time of the total system.

Parasitic Impedances of the Connection
The parasitic impedances of the connection to the individual chips significantly influence the current sharing between the chips operated in parallel. In case the parasitic inductances are not equally designed for all chips, a dynamic current imbalance during IGBT switching will occur. The module terminal arrangements and the chip positions are the major influencing factors for the parasitic impedances. To realize an equal impedance, the distances from the power terminals to all the chips have to be ideally the same.

This can be achieved by optimizing the terminal and chip arrangement so that it is perpendicular to the current flow as shown in figure 3 . In the ideal module concept, the commutation (indicated by the blue and red arrows) is only in Y-direction whereas the terminals and chips are orientated perpendicular in x-direction.

By this approach, equal parasitic impedances are achievable. This ideal concept was considered in the development of the LV100 layout and a homogenous current sharing, as shown in the simulation result in figure 4 was realized.

Conventional Modules
The conventional modules available today in the field of high power industrial drives or converters for renewable energy usually have a terminal arrangement which is parallel to the chip arrangement and current flow. As a result of this conventional design, equal parasitic impedances was not be realizable and the resulting imbalance in the current sharing was an accepted feature of the conventional modules. For events such as load short circuits, due to the absence of the inductive coupling in the laminated busbars, the impact of the unequal stray inductances between different chips becomes significant for such conventional modules.

SiC Devices
In case of fast switching semiconductor devices with high di/dt, the differences in parasitic stray inductances between the chips will influence the current sharing enormously. Therefore, if an Inverter designer considers changing to SiC devices in future, the LV100 package is the right choice since the layout concept is ready for SiC . As result, a potential future change from Si-IGBT to SiC-MOSFET devices is feasible with less changes and redesign efforts.

Thermal cycle failure-free package
IGBT modules in high power industrial drive applications experience thermal cycling in case of fluctuating (or non-continuous) loads. Wind power converters are usually liquid-cooled with the cooler having a thermal time constant of a couple of seconds. As a result, the IGBT case temperature will respond rapidly to a temperature swing by changing of load conditions. That means on days with fluctuating wind conditions the IGBT module baseplate will experience many thermal cycles. Also photovoltaic inverters experience at minimum one huge thermal cycle per day. Considering an inverter life-time of 25 years, the IGBT module have to be capable to resist several thousand thermal cycles.

The thermal cycle capability of conventional industrial IGBT modules with conventional package structure (with several pieces of ceramicling substrates solder to copper baseplates), is limited. Hence thermal cycles have to be considered as lifetime limiting parameter during the converter design. To eliminate thermal cycling as lifetime limiting parameter, the SLC-Technology has been selected for the LV100 development for industrial application. As shown in figure 5, the conventional power module package structure is replaced by an IMB (Insulated Metal Baseplate) in combination with a direct potting resin.

The thermal expansion coefficient of the insulator and the potting resin are matched with each other (considering the thermal expansion of copper base- and pattern-layer. Due to this matching thermal expansion and the elimination of system solder layer, a thermal cycling failure free package structure has been realized .

7th gen 1700V IGBT chip-set
The 7th gen IGBT and diode chips possess an optimized structure and are thinner than its predecessors. Additionally, the devices have been designed by selecting an appropriate trade-off between the DC performance and the switching performance .

NEXt Genaration IGBT
NEXt Genaration IGBT

The inverter losses under typical application conditions for high power converters has been performed by Mitsubishi Electric Melcosim simulation software. In figure 6 the result and comparison of 1200A/1700V LV100 vs a conventional 1400A/1700V module from company A. It is noticeable that for a switching frequency of 500Hz the total losses are comparable. However, due to the appropriately selected trade-off in combination with the optimized chip structure, the diodes and the IGBTs indicate switching losses are significantly reduced.

The result is that for switching frequencies higher than 500Hz, the LV100 has significantly higher efficiency. For example, at a switching frequency of 5kHz the loss reduction is 39%. This loss reduction contributes to reducing the cost of the total inverter by reducing efforts for cooling and enabling to achieve higher power density of the system.

A new high power IGBT module (LV100 for industrial) is under development, which has been optimized for the requirements of high power applications in the field of renewable energy converters, and industrial drives. The outline of the module housing is same as HVIGBT LV100 and in line with the new market defacto standard. The SLC-package-technology is thermal cycling failure free and improves the reliability of the system.

The 7th gen IGBT chip technology provides a significant reduction of switching losses and is beneficial considering a switching frequency from 500Hz onwards. The internal layout has a minimized stray inductance and ensures a homogenous current sharing between the chips. Therefore, it is feasible to use this layout with fast switching semiconductor.