No matter which manufacturing technique or process is used for plastic moulds, there is always quality control procedure to ensure that no inferior products are released into the general circulation or sold to the buyer. When it comes to injection moulding technique, there are several different tests and control points placed throughout the manufacturing process to ensure that the final product is meeting the defined standards.
Here, we will discuss some of the common issues encountered during moulding process which affect the quality of final products.
Sink Marks:
In plastic injection moulding, there are some obvious display issues that can be detected through visual inspection. Different problems may be encountered throughout the manufacturing process based on different factors such as heat, the material used, setting time and several other variables. Sink marks are the most common among them. A sink mark is typically a dimple in the outer layer of the plastic which occurs when the plastic is soft and still in the molten state. As the material cools and compacts, sink marks become visible in the product.
Liquid Plastic Flashing:
A flash usually occurs in the plastic products when two different parts of mould are melted together. If two pieces of molten plastic come in contact with each other too quickly, they can fuse together and will not be dislodged. Many times in injection moulding manufacturing process, two products or parts are placed together when they are in late cooling phase and their temporary bond can be easily detached and broken.
However, if they are placed together when the liquid plastic is still solidifying, they will be fused with each other and their detachment would either require a knife or they may not detach at all. In such cases, quality control services make sure that all inferior products are identified and none of them are sent to the clients.
Burn Marks:
When the plastic is left in the moulding cavity for a long time and it is scorched from the extreme heat. As a result of this, gas marks or burn signs occur. These types of marks may also occur when hot compressed air inside the mould doesn’t get to escape and slowly builds up inside it which eventually scorches the plastic.
Knit Lines and Short Shots:
Short shots appear when there is not enough plastic used in the mould. This lead to soft corners, chips or areas of mould may simply not appear. On the other hand, knit lines occur at the place where two areas of plastic mould came in contact initially.
For achieving fine finish, the mold material should maintain a uniform look from one piece to next. Since such marks occasionally occur either due to lack of knowledge or negligence, it is necessary to inspect each of the items.
There are also more complex issues which need testing from
quality control experts. So, if you want to be sure of that each of your moulds and products are meeting the highest standards, hire quality control services and enhance customer satisfaction by delivery defect-free products.
