Why automobile plastic mold shrink , how to solve?

Plastic products shrink is an inherent characteristic of the plastic mold products, because of thermal expansion and contraction causes.

When the injection mold products, the temperature is high, When finish auto plastic molding mold, temperature is low, Volume will be reduced, as to reduce the number of plastic mold products mainly to see what material!

For example, ABS shrinkage is 1.005, if done forming the size of 1000 plastic mold, die size should be 1005, Auto Mould size reach 1005, so that the size of automobile parts mold injection molding products out before they can meet the requirements.

A Successful Plastic Injection Mold for Fuel Pump ​component on Automobile

WIT Mold has just successfully built a 4-cavity plastic injection mold for a German customer. The plastic mold part is a component for automobile fuel pump. The part material is POM, and the part weight is 19 grams. The mold size is 790*500*505mm, and its weight is 800 kg.

There is a barb feature surrounded by a circular wall, the tight space makes it unfeasible to form this barb by traditional slide or lifter. WIT Mold designed custom expandable cavity for this feature. The untilization of expandable cavity provided solution for releasing undercut in a tight space area.

4 latch locks of Strack brand are installed on the sides of the mold. They provide stable actions in sequenced mold opening and closing.

Components for automobile fuel pump mold are high precision parts. For this part, all the dimensions listed on the part print need to be in specification. Because of the large range of shrinkage rate of POM, it is not easy to make accurate dimensions on a POM part. How ever, with high precision measuring equipments and rich experience, WIT Mold overcame these challenges. Our customer approved the samples of the 2nd trial.

For more details of this mold, please review our website.

Family mold in plastic mold, the reason is what affects the size precision plastic parts

According to the size of the production capacity, product structure, to determine the appropriate number of cavities, more cavities, precision molds, processing difficulty, the higher the cost of the mold. However, injection molding unit price will decline.

Impact of multi-cavity Dimensions factors:

1. precision mold machining. For example, the discharge cavity, each cavity is a discharge, if the discharge process control is not good, there will be the size of the cavity bias.

2. the mold assembly precision. Because of the internal structure of the assembly causes the position deviation.

3. mold design factors, such as the flow channel design is reasonable, into the plastic is uniform, unreasonable runner nozzle chamber so close to advanced gum, gum away from the backward because contraction inconsistent, pressure conditions also lead to inconsistent dimensions appear deviations. Into the plastic mouth diameter size will cause the size of the deviation.

4. mold waterway design is unreasonable, in each cavity layout should be uniform cooling water, if it is unreasonable to different temperatures in different parts of the mold, resulting in shrinkage is different, so the size of the deviation.

In short, family mold problems are basically the size of a deviation in the mold. Injection molding process has little effect.

Medical equipment mold and general injection mold is different, what should pay attention to ?

Medical mould devices are divided into a lot of kinds, some products do not contact with the human body, some contact with the human body, sometimes into the body, is different to the requirement of mould material.

According to the nature of your product, no product contamination, determine the mold material, as long as to achieve the purpose of without causing harm users, of course this is at the very least, as for the requirement of the rust and prevent the respect such as deformation, should also be taken into account.

Wit mold limited has good expensive with medical mould, Let us discuss

Selective laser sintering insert greatly reduces lead-time of mold manufacturer

Selective laser sintering insert greatly reduces lead-time of mold manufacturing

Metal powder composite forming method is an integration of Selective Laser Sintering (SLS) and common CNC machining, it is the combination of Lamination modeling and opposite reductive manufacturing, this method unite advanced material, software, laser and CNC technology. The part accuracy can reach up to ±0.005mm, and the hardness after heat treatment can reach up to Hrc54, satisfying the dimension and hardness request of a precision plastic injection mold. Consequently the customer and tool maker got a very valuable solution for manufacturing of mold component.

For the past few years, the effort of bringing rapid prototyping technology into injection mold industry has never stopped. Especially in Europe, Selective Laser Sintering (SLS) and Selective Laser Melting (SLM) have been successfully used to directly make a metal part. And now the development has reached the level of directly making components for plastic injection mold as experiment.

Metal powder composite forming method process

The manufacturing process is:

①The laser sinter the metal powder on first layer

②Cover the second layer powder and sinter again and again until the material is thick enough for the cutter

③The CNC cutter machines the material

④Repeat step 1 to 3 again and again

⑤Finally got a finished part

　　

an Automobile Injection Mold successful Project

WIT MOLD has just successfully built a large plastic injection mold for an American customer. This part is used on automobile, serving both decorative and structure function. The part material is PP resin, and its weight is 776 grams. The mold weight is 5500 kg and its size is 1500*800*700mm.

There is a bunch of shut-off holes on the part. 7 pcs slides and 6 lifters are employed as side action solution for the undercuts on the part. With sophisticated craftsmanship of our mold making team, all the shut-off holes are nicely flash-free. Our specialty at side action solution provided smooth movement and precise position for each slide and lifter. Despite the large size, WIT MOLD efficiently got automotive mold production ready with only 4 trials.

For more detail, please review our web site.