• Why Use Foam Injection Molding ?

    China has started ban of the production and sale of cars using traditional fuels. At present, Nissan, BAIC, Volvo, Changan Automobile and other car companies have announced their schedule of phasing out fuel vehicles and move towards of development of new electric vehicle.  However, subjected to the mileage of electric vehicles, lightweight issue has become one of the tops ones that needs to be addressed urgently by vehicle manufacturers. Therefore, Micro-foam injection molding technology technology is more and more widely used.     What is Foam Injection Molding? Injection Foam Molding is a low-pressure process where molten resin is injected with nitrogen gas or a chemical blowing agent. The resin is then shot into the cavity, without overfilling or packing it out. The blowing agent or gas then expands to push the molten resin to the extremities of the cavities. As the part cools, the internal pressure of the foaming action takes up the internal shrinkage and reduces sinks over ribs or heavy cross-sections.  …

  • Mold cavity has a smooth-polished surface and your ABS molding part is too dull?

    Have you ever met the case when the cavity steel has been polished as high as possible but the ABS molded part is still not at the gloss needed? The problem may be related to mould, material, processing, or combinations thereof. Look at below information to find the root cause.   Plastic injection Mold   Surface of cavity steel is not clean Oil or water stain on the surface of cavity steel, and too much release agent applied during the process of abs injection molding, all this create a dull appreance. In this case, clean the mould and control the use of mold release agents.   Mold or Part design   When the wall stock varies, it is very difficult to maintain consistent gloss on the part. Depending on the flow pattern, thinner wall sections may not be exposed to as much plastic pressure, and the result is excess gloss in that area. The same effect can happen when the…

    Injection molding process March 10, 2020
  • How to calculate mould shrinkage

    Thermoplastics shrink as they cool and solidify during the plastic injection molding process and after part ejection.   The plastic injection mold cavity is machined larger than the final desired molded plastic part size in order to compensate for part shrinkage as the part cools.   Mold shrinkage data for the specific plastic material can be used to calculate the amount of mold expansion needed.     Shrinkage in mould units are expressed as length-per unit-length, or as a percentage, and is calculated using the following mould shrinkage calculation formula :     (mold dimension – part size) / mold dimension  = Mold Making Shrink Factor   We could alse use a simplied formula as below.   S={(D-M)/D}×100%(1)   Shrinkage; D-Mold Size; M-Molded part size   However, since the actual shrinkage is influenced by many factors, only the approximate value can be used,When building the mould, the cavity should be machined according to the lower deviation while the core be machined according to the upper deviation to leave…

    Injection molding process February 29, 2020
  • Injection Molding Defects Delamination

    What is delamination/Peeling? Delamination is thed detached, slate-like surface layering of the polymer as it fills and packs the plastic injection mould tools. With this defect, different unconnected layers of plastic develop and form within the plastic injection molded parts. , e.g. due to cross cutting. usually not easy to identify since the surface is flawless; a “skin” can often be pulled off when the surface is scratched with a blade. The molded plastic product exhibits bubbling after warm storage. The cause of delamination High shear stresses result in the formation of layerseven in compatible multiphase systems during injection molding process. Contamination with an incompatible thermoplastic or master batch Sharp Corner around the injection gate and runner in the plastic injection mold Correction Increase the melt temperature and reduce the injection speed. Avoid contamination due to extraneous material or due to an unsuitable master batch (specifically the carrier) Channge all shapr corners to be round corner….

    Injection molding process February 23, 2020
  • What causes weld lines in injection molding

    What is weld lines in injection molding  During the manufacturing of injection molding process , the Weld lines , also calles as Knit lines or Meld lines are present on the surface of plastic molded parts where two flow fronts meet and when they are not able to to “knit” together, or “weld” together .These harilines or dark lines usually occur around holes or obstructions and cause locally weak areas in the molded resin part. Appearance of weld lines in injection moulding  Notches, hairlines Change in apparent color; especially when inorganic decorative effect pigments are used the weld line appears as a dark line; conspicuous in dark, brilliant or transparent moldings having smooth surfaces polished to a high gloss. Cause of weld lines injection molding Appear in multiphase systems such as ABS or ASA. Flow fronts having an already cooled peripheral layer encounter one another and no longer allow fusion without marks. Decorative effect pigments and, e.g., glass fibers tend to straighten up in the…

    Injection molding process February 20, 2020
  • Injection Mold tryout guideline

    As known, the manufacturing of plastic injection mold determines the quality of plastic molded parts, production effieciency and cost of finished products.Mold trial is run to solve any problems with the design, resin, tooling,machine. Thus procedures of mold trial is very important for a injection molder. Be sure to follow this nine-step process to make sure you’ll be making good parts through a successful trial.   Firstly, Keep the  injection mold run on the press without any resin to verify the function of  the mold    A. Check mold opening and closing condition at low pressure:   Mold should beopened and closed by 3 times at fast, medium and slow speed. During the process, there should be no abnormal sound nor block phenomenon;   Mold opening and closingshould go smooth  without any interference.   B.Checkejection system of the injection mold (at low pressure)   1.Check the ejection action at  fast, medium and slow speed.   2.Check whether ejector pins  or sleeves on the…

    Injection molding process February 17, 2020
  • How to solve silver streaks in injection molidng

    Silver streaks are a very common phenomenon appearing on the surface of plastic injection molded products. They are shining line shaped patterns usually caused by moisture, but can also be caused by high filling rates and poor vents which can cause entrapping of gas either from the environment, mold water leaks, etc. These can be considered external appearance quality defects in exterior parts of consumer electrical products, automobiles, motorcycles, etc. The most commonly seen streaks are shown as below. Moisture streaks/splay marks Burning streaks/silver streaks   Dark streaks Color streaks     The cause for the formation of streaks can be deter-mined in many defective injection products only after costly investigations,especially as the appearance of burning and moisture streaks is similar.Extensive knowledge of the plastic,the mold design and the plastic injection molding processing are indispensable for overcoming the problem.Before launching expen-sive and time-consuming investigations the following points should be checked in the sequence given and if…

    Injection molding process January 17, 2020
  • How to Troubleshoot Flash Defect on Two Shot Injection Molding 

    What is flash in two shot injection molding? Description  2nd material penetrating between 1st material and its cavity. It is observed frequently where 1st material shrinkage is big and cooling time for 1  material is too long. It is mainly due to too fast shrinking of 1st material.   How to trouble shoot the flash? 1.Optimizing holding pressure & Cooling time to get min shrinking of 1st material till before 2nd shot molding. 2.Select less shrinkage rate material for 1st shot. 3.Changing design as preventive action. We’ve spent the past 15 years accumulating rich practical experience in solving the flash of two-shot injection molding. HS Mold has the design, engineering, and in-house tooling capabilities you need to streamline your project 2k injection molding project from conception to production.              

    Injection molding process January 3, 2020
  • Tips on Injection Molding Technolog of POM Plastic parts

      What is POM? POM,,also calles as acetal, Polyoxymethylen is a kind of thermoplastic plastic particles with high hardness and rub resistance. The resin is applied to the production of precisions parts requiring highstiffness, low friction, and excellent dimensionalstability. The POM injectin molding is a crystalline plastic process with an obvious melting point.  Once the melting point is reached, the melt viscosity decreases rapidly. When the temperature exceeds a certain limit or the melt is heated for too long, it will cause decomposition. Copper is a catalyst for POM degradation, therefore avoid using copper or copper materials on the areas contacting with POM melt.   POM plastics   English name: Polyoxymethylene (Polyformaldehyde)   Properties of POM Plastics   Density: 1.41-1.43 g / cubic cm   Molding shrinkage: 1.2–3.0%   Molding temperature: 170-200 ℃   Drying conditions: 80-90 ℃ for 2 hours   Eingeering plastic POM   Reinforced POM   The main reinforcing materials are glass fiber, glass ball or carbon fiber, etc., and glass fiber is…

    Injection molding process December 16, 2019
  • An quick tip to improve injection molding process within 5 minutes

    Well, this is an important technique that could help injection molders to improve molding process within a few minutes. The technique could be summarized briefly with a few words “first fast and then slow shoot”,i.e, first rate injection speed until the fill is complete on the  preset position and then use second rate slower shoot which usually starts at the end of fill. Rapid injection speed helps to maintain the temperature of the molten plastic and overcome the resistance from mould cavity, which gets  the plastic fill completed smoothly. On the other hand, the slower shoot   is a good way to vent the trapped air, preventing flash and shrinkage problems. Skilled Application of this technique can also help to trouble shoot many difficult molding problems .   1.It can be used to solve the trouble of trapped air in injection molded parts,including air stuck in “dead corners”   2.It is used…

    Injection molding process November 25, 2019
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