Month: May 2019

injection molding defects

How to eliminate injection molding defects?

Klarm Mould

Injection molding is an art, which involves science as well. Actually, injection molding requires great attention to detail as minor mistakes can cause a lot of financial loss to a company. In this article, we are going to discuss how you can eliminate common injection molding defects.

injection molding defects
injection molding defects

Flow Lines

Flow lines may include lines, patterns, and streaks that appear on the prototype part because of the cooling profile or physical path of the molten plastic while it moves into the cavity.

Fix:

  • One way to fix the issue is to increase the pressure and injection speed, which will make sure that the mold will fill the cavities.
  • Another way is to round the locations and corners where the thickness of the wall changes.

Sink Marks

These are minor depressions or craters that form in the thicker areas when shrinkage happens in the internal areas of the end product.

Fix:

  • Reduce the mold temperature, increase the holding pressure and time for better curing and cooling.
  • Reduce the thickness of the wall sections that are the thickest. This will allow faster cooling and prevent the sink marks.

Vacuum Voids

Vacuum voids refer to the air pockets inside or near the prototype surface. They occur because of the uneven solidification amidst the inner sections and the surface.

Fix:

  • Find the gate at the mold’s thickest part
  • Opt for the plastic that is less viscous, which will reduce the amount of gas trapped.
  • Increase the holding time and pressure
  • Try to keep the mold parts aligned

Surface Delamination

Surface delamination happens when thin layers of the surface show up on the part because of a contaminant. Actually, these layers look like coats that can be peeled off.

Fix:

  • Before molding, make sure you dry the plastic properly
  • Raise the degree of mold temperature
  • There should no sharp turns and corners in the mold design

Weld Lines

Weld lines show up on an area where the liquid plastics mixes while they flow from different injection mold parts.

Fix

  • Increase the temperature of molten plastic or mold
  • Raise the injection speed
  • Make adjustments to the design to ensure that the flow pattern is only one source flow

Short Shot

Short shot refers to a situation that happens when a molding shot tends to fall short. In other words, the molten plastic won’t fill the cavity of the mold for some reason. As a result, it leaves a portion where you can see plastic.

Fix

  • Opt for a plastic that features higher flow and less viscosity
  • Raise the mold temperature for better flow
  • Get a machine that features more material feed

To cut a long story short, you may have to face a lot of defects during the process of injection molding in China. What you need to do is follow the tips given in this article to fix or eliminate these issues to make the process error free. Hopefully, you will find these tips helpful.

Resource box: This article is originally posted in https://www.injectionmouldchina.com.

injection molding difficulty

Difficulties of molding different plastics on injection molding

Klarm Mould

When it comes to plastic injection molding, manufacturers have a lot of problems and difficulties to deal with. Manufacturers use plastic for many reasons, such as design flexibility, affordability, and lightweight, just to name a few.  Making parts and designs with injection molding has some difficulties. Let’s take a look at them.

injection molding difficulty
injection molding difficulty

During the injection molding process, you may have problems, such as parts deformation, structural weakness, surface blemishes, warpage, shrinkage, parting lines, voids, and air traps, to name a few.

All these problems may add to the cost of manufacturing. For streamlining the process, you have to use the trial-and-error prototyping process in a virtual environment.

Making tools that can help make high-quality injection-molded parts requires you to consider a lot of variables. For instance, it includes the optimal temperatures of the plastic, cooling channels, and the configuration of these systems, to name a few. Aside from this, you also need to consider pressure, flow rate, thermoplastic material type, solidification time, and so on.

If you have the required mold-filling simulation, you can easily balance the design against manufacturability. Moreover, mold makers can choose to optimize tools without the need for prototype molds. This way the manufacturers can also reduce run cycles, which results in better quality, reduced costs, and less time consumption.

Actually, the primary factor that you need to keep in mind in order to avoid the traditional problems associated with plastic injection molding is the accuracy of simulations.

Evaluating Manufacturability

With plastic injection molding simulation, designers can get answers to common questions related to part filling, air traps, voids, and gate locations, to name a few. With the help of these analyses, designers can perform the simulation of the mold-filling stage in order to understand whether it can speed up the tooling design and production process.

Optimization of the Mold Design

The primary goal of a Chinese mold maker is to develop injection molding tooling that can produce quality parts without costing a lot of money. Moreover, this simulation offers extra tools to optimize tooling designers of different complexity levels. And this helps mold makers simulate different phases like filling and packing.

Improving Cycle Times

It’s really important to reduce cycle times by ejecting quality parts in the shortest time span possible. If advanced capabilities are used, plastic injection molding can help specialists hit the best balance between quality production and short cycle times.

All of this helps the designing and simulating of the cooling line layouts, processing parameter optimization and the making of conformal cooling systems.

Improving Mold-Filling Simulations

Nowadays, manufacturers can enjoy a lot of benefits by molding plastic parts instead of using the traditionally machined parts. For instance, they can reduce costs, scrap, weight and increase the design flexibility via the production of design and shape geometries that are more complex.

However, they can only enjoy these benefits if they boost the design and the productivity of the tooling. Nowadays, manufacturers can improve the performance and efficiency of their operations if they choose to replace or improve the conventional mold using the mold-filling simulations.

So, this was a description of some of the difficulties that manufacturers face during the plastic injection molding process and how these problems can be fixed.

Resource box: This article is originally posted in https://www.injectionmouldchina.com.