Medical molds design and use specifications

Medical molds are very demanding molds, and the product inspection standards are extremely high. In addition to high-precision processing, it is also necessary to understand the purpose of this product, as well as the national inspection standards of the Quality Supervision Bureau. Some products require clinical testing to determine whether they are qualified or not，As an important part of medical mold core pin is extremely strict

The main difficulty of the core pin is that the core size accuracy of the needle tip is not easy to control, and even high-precision equipment may not be able to be processed in place; the size of the Luer connector at the bottom is designed according to the 6:100 slope, which must be strictly in accordance with National standard testing, the actual accuracy may be 0.005-0.01mm, otherwise there will be water leakage, and the core pin processing scrap rate is very high.

First of all, in the selection of core pin raw materials, it is necessary to choose high hardness, steel with HRC35° or more is the most suitable, generally SKD61/S136 steel is used. The heat treatment deformation is small, and the discharge performance is excellent.

Secondly, the control of machining accuracy is particularly important, because the trocar needle product is very small, the smallest hole size is only 1mm in diameter, and the concentricity of the core pin must be ensured. This is a test of the accuracy of mold processing personnel and processing equipment. When selecting processing equipment, we choose imported high-speed lathes, and try to use equipment that has been used for less than 5 years, because the actual processing accuracy of the equipment that has been used for a long time has deviated, which will directly affect the molding of the product. For the electric discharge machining of the needle, the copper electrode is not easy to wear. After the high-speed precision carving is in place, the mold is matched and then the mirror electric spark is used to strike it in place (the attention should be paid to the machining spark gap control).

Third: The choice of glue port. Generally, this product will use a multi-cavity design structure. The mold adopts imported hot runner to turn latent glue. Because the glue mouth is on the inclined surface, it is easy to pull the glue mouth. At this time, the latent glue is EDM is particularly important, and the spark gap should be within 0.01mm as much as possible.

Fourth, medical devices, especially tubular products, are disposable products and the product volume is large. Generally, more than 8 cavities are required, and more than 64 cavities are required. This is necessary for mold feeding and other systems. High requirements, the mold core must take into account the needs of heating or heat dissipation. Threeup’s products suitable for core pin heat dissipation mainly include water transport pins and heat pipes. It is worth mentioning that the heat conduction pipe, the thermal conductivity is 200 times that of the copper pipe, which can quickly conduct the heat inside the core pin.

The technical requirements for plastic parts of medical products are that there must be no peaks, dissatisfaction with injection molding, material flow lines, poor gloss, pores, warpage deformation, silver streaks, poor demolding, gas scorching, cold materials, jet lines, bubbles For various defects such as, discoloration, etc., mold release agents shall not be used in the molding of plastic parts. The shell meets the basic requirements of plastic parts for medical devices. This has put forward high requirements for the overall requirements of medical moulds as well as the core pin design and production of medical moulds.

Cosmetic mold test common sense

Improper design of cosmetic packaging molds will often cause defects of one kind or another in the final product, so it is necessary to conduct good tests on cosmetic packaging molds. Before modifying the mold, try and evaluate the mold and optimize the mold design and process parameters, Especially the design and installation of core pin. which can usually achieve a multiplier effect with half the effort, while meeting the high-quality requirements of mass production.

A: Why do you want to try out the mold design for cosmetic packaging materials?
Most of the molded products of cosmetic packaging materials, the defects are caused in the plasticization and injection molding stages, but sometimes they are also related to improper mold design. Possible influencing factors include: the number of mold cavities, core pin design, and cold/hot runner system Design, the type, location and size of the injection port, and the structure of the product itself. Therefore, in order to avoid product defects caused by mold design, we need to analyze the mold design and process parameters when making the mold, and even consider the temperature control of the mold core pin.
After obtaining the mold trial results, the operator usually needs to evaluate the specific conditions of the mold, so as not to increase unnecessary costs and time in the process of modifying the mold. In most cases, this evaluation also includes the setting of machine process parameters.，Is the core pin design and mold release convenient?  In other words, in order to make up for the deficiencies in the mold design, the operator may make incorrect settings without knowing it. In this case, the production and operation process of the equipment is abnormal, because the parameter setting range required to produce qualified products is very small. Any slight deviation in the parameter setting may cause the quality of the final product to far exceed the allowable The error range of the result is much higher than the cost of mold optimization in advance. For example, the quality of core pin, whether it can be produced normally, the purpose of making cosmetic packaging material mold trial is to find out the optimized process parameters and mold design. In this way, even if the materials, machine settings or environmental factors change, a stable and uninterrupted mass production environment can still be ensured, not just to obtain a good sample. this point is very important.

B. Preparation of cosmetic packaging material mold before mold trial
1. Understand injection products: Engineers need to understand the shape and structure of the product in advance, the structure and product characteristics that are prone to problems, and pay special attention to the core pin of the key part of the molding, so that they can quickly find out and adjust and solve them in time.
2. Prepare drawings: prepare trial drawings before T1. If there is no drawing provided by the customer, the manufacturer needs to mark the length and width of the product according to the 3D mold opening size,  Sometimes we can also determine the size of the product according to the size of the core pin of the mold.  which is convenient for caliper measurement, at least 2 sizes, so that it can be adjusted in time during the trial. .
3. Prepare measuring tools: According to the size of the drawings, prepare suitable measuring tools, or inspection tools, and suitable samples for measurement and verification.
4. Familiar with the physical properties of raw materials and processing conditions: The engineering needs to be familiar with the physical properties of the raw materials, and be able to judge on the spot whether the molding conditions are within a reasonable range.
5. Issuing a test mold notice: According to the product weight, mold characteristics, size and conventional requirements, the project will issue a test mold sheet to facilitate the arrangement of suitable machines for production pipes. The test mold sheet needs to indicate the water connection method and requirements,  Pay attention to observe whether there is any design cooling water passing through the core pin, if so, avoid clogging of the water hole inside the core pin. and the mold flow conditions will be given priority. Try out the mold.
6. Determining the equipment: It is also necessary to confirm the auxiliary equipment for the mold test, such as the number of water pipes required by the mold, the number of water source interfaces and the performance of the basic hardware facilities can meet the requirements of the mold test, and the need to prepare a thermometer.
7. Notify relevant participants: Quality personnel must be notified to participate before mold trial. For important molds, mold projects, product projects, fitters, and designers must be notified to participate. Mold core pin is a relatively important part. If the core pin is provided by other suppliers, it is necessary to report the core pin problem to other suppliers as soon as possible. If mold problems reach the company’s technical bottleneck, various departments will discuss plans on site.

C. The basic process of cosmetic packaging material mold trial

In order to avoid unnecessary waste of time and troubles during mass production, it is indeed necessary to pay patience to adjust and control various processing conditions, find the best temperature and pressure conditions, and formulate standard test procedures, which can be used in Establish daily working methods.
1. Check whether the plastic material in the barrel is correct, and whether it has been baked in accordance with the regulations (if different raw materials are used for trial and production, different results may be obtained).
2. The material pipe should be cleaned thoroughly to prevent inferior glue or miscellaneous materials from being injected into the mold, because inferior glue and miscellaneous materials may jam the mold and core pin. Test whether the temperature of the barrel and the temperature of the mold are suitable for the raw materials to be processed.
3. Adjust the pressure and injection volume to produce a finished product with a satisfactory appearance, but do not run off the burrs, especially when some mold cavity products are not completely solidified, you should think about it before adjusting various control conditions,  Some longer core pins need to consider separate cooling, so as to shorten the production time， because the mold is filled A slight change in the rate may cause a large change in the filling of the mold.
4. Wait patiently until the conditions of the machine and mold stabilize, even for medium-sized machines, it may take more than 30 minutes. You can use this time to view possible problems with the finished product.
5. The advancing time of the screw should not be shorter than the solidification time of the gate plastic, otherwise the weight of the finished product will be reduced and the performance of the finished product will be impaired. And when the mold is heated, the screw advance time needs to be prolonged in order to compact the finished product.
6. Reasonably adjust to reduce the total processing cycle， Adjusting the cooling rate of the core pin is a way to adjust the mold production cycle.
7. Operate the newly adjusted conditions for at least 30 minutes until it is stable, and then produce at least a dozen full mold samples continuously, mark the date and quantity on the container, and place them according to the mold cavity to test the stability of the actual operation And derive reasonable control tolerances. (Particularly valuable for multi-cavity molds).
8. Measure and record the important dimensions of the continuous sample (the sample should be measured when it cools to room temperature).
9. Compare the measured size of each mold sample. Note: ① Whether the size is stable. ②Whether there is a trend of increasing or decreasing in some dimensions, which indicates that the machining conditions are still changing, such as poor temperature control or oil pressure control. ③Whether the size change is within the tolerance range. ④Are the products from each core pin consistent?
10. If the size of the finished product does not change and the processing conditions are normal, it is necessary to observe whether the quality of the finished product of each cavity is acceptable and its size can be within the allowable tolerance.  Whether each core pin can work normally. Note down the number of cavities that are continuous or larger or smaller than the average to check whether the size of the mold is correct.

D. Precautions for mold trial of cosmetic packaging materials
1. Prepare the DFM: The engineer in charge needs to prepare the DFM to check the mold structure in detail. If there are any problems, you need to find out on the spot. Especially carefully check the core pin.  If there is something wrong, you need to record it in the mold test condition table and feedback and correct it.
2. Check the water connection method and various condition settings: the project needs to be one by one water connection method (following DFM one in and one out), mold temperature setting, barrel temperature setting, inspection of injection conditions, core pin operating status If there are non-conformance items that need to be corrected immediately, if they cannot be corrected immediately, they need to be recorded in the test mold condition table so that the problem can be improved during the review.
3. Product injection 90%~95% full: The product measurement needs to be estimated before the product is shot, and the holding pressure switch position should be advanced according to the MOLD FLOW condition. The product needs to be held at 0 pressure, and the shot is slow and the product is 90-95% stable And keep the screw storage material about 10% (when the mold has a mold with multiple cavities, you need to see whether the feed of each cavity is uniform, and whether each core pin is working properly, otherwise you need to keep the sample to facilitate mold adjustment) and then slowly increase the pressure of 10 Pressure until the product looks its best.
4. Confirm the size and appearance: When the appearance of the product is adjusted to an acceptable state, take 2 molds and soak in water for 2-5 minutes, and then measure the size. Based on the product size, adjust the size to the figure without assembly requirements. The surface median limit. secondly, adjust the core pin appearance of the structure and fine-tune the injection parameters, and print out the number of samples required under the best conditions of the appearance and structure (confirm shrinkage, burrs, lack of material, bonding lines and other defects), and record the conditions and the molding condition table for the next time Use, if you cannot overcome the need to keep sample records, it is convenient to review and improve countermeasures.
5. Confirm the mold temperature and the water inlet and outlet temperature of the water pipe: before injection and 10 molds, after 30 molds, it is stable at least three times. The temperature of the inlet and outlet of each water pipe needs to be measured. The temperature difference between the inlet and outlet water temperature of each inlet and outlet should not exceed 3 degrees, if any The difference needs to be checked immediately for the water flow and whether it is connected incorrectly, Check if the water transport of the core pin is blocked.
In addition, the measured temperature of the mold surface needs to be measured. According to the size and shape of the product, the temperature of large products needs to be measured at least 5 points.  If there are more core pins, at least 20% of the core pin temperature needs to be measured to see if they are consistent.   If there is a large temperature difference, it needs to be confirmed. When the mold temperature is stable, the measured temperature needs to be recorded on the mold surface (take the average value) ), the surface temperature of the mold needs to be within the recommended range of the physical property table, if it cannot meet the requirements, you can try to change it if allowed.
6. Confirm the mold clamping situation: If the product has burrs after being printed, you need to call a fitter to be there immediately, spray a red mark on the machine, and close the mold with the maximum clamping pressure at low speed and low pressure about 30BAR to confirm the tightness of the mold fit.
7. Many cosmetic packaging molds with screw teeth are ejected by core pin rotation and other methods. Pay special attention to whether each core pin can work normally during mold trial.
8. Early detection and early resolution of the problem: If there are deformations, size problems, core pin damage, etc. in the soft mold stage, it is necessary to work hard to solve it in the soft mold stage, otherwise it will lose the meaning of mold opening.
9. Mould change steps: When the mould needs to be changed, the customer needs to be notified, and the mould cannot be modified privately. Any changes need to be approved by the customer.
10. Data preservation: properly keep all the records of sample inspection during the mold trial process, including various pressures during the processing cycle, melt and mold temperature, barrel temperature, injection action time, screw feeding period, core pin appearance, etc. In other words, it is necessary to save all the data that will help to establish the same processing conditions smoothly in the future in order to obtain products that meet the quality standards. At present, the mold temperature is often neglected during mold trial in the factory, and the mold temperature is the most difficult to grasp during short-term mold trial and future mass production. Incorrect mold temperature can affect the size, brightness, shrinkage, flow pattern and lack of material of the sample. , If the mold temperature controller is not used for mass production in the future, there may be difficulties.