Top 10 Injection Molding Defects of Plastic Products - #Part 2

When you want to purchase plastic products from a plastic food containers manufacturer, what you should care about? I believe that the upmost issue you care about will be quality.

In the previous article, we’ve introduced 5 common injection defects, including weld lines, voids, burn marks, declamination and jetting. In this post, let’s check 5 more molding defects you should be aware of.

1. Flash.
Flash appears when escaped molten plastic cools down and attaches to the finished product . It might cause a thin lip or protrusion through the parting line or ejector pin locations.

Flash -Easylockware.com

2. Knit Lines.
Knit lines are also called weld line in injection manufacturing. It’s the line where two flow fronts meet and knit together. Knit lines usually appears near obstructions and holes which can cause breakage when the part is under stress.

Knit Lines - Easylockware.com

3. Flow Marks.
Flow marks are molten plastics that become solid during the injection process. It appears especially on narrow sections of the molded component as patterns, streaks or wavy lines that are in off-toned color. The slower the injection speed is, the evident the flow marks are.

4. Sink Marks.
Sink marks are small craters or depressions that appears in thick areas of injection molded surface resulted from shrinkage in the inner portions.

Sink Mark - Easylockware.com

5. Warpage.
Warping is the deformation that result from uneven shrinkage. It occurs as twisted, uneven, or bent shape plastic products.

There are many other injection molding defects that we haven’t mentioned about. Either the molding machine, the mold, the plastic material or the molding machine operator are the possible causes of plastic molding defects.

Even though there are many different reasons that will lead to plastic injection defection, We are proud to tell you that raw material we use is pure and top, the molding machine and molds are regularly checked and our engineers and workers are well-trained. We are good at pre-solving any possible factors and our skilled QC team do inspections on every steps for double check. Easylock plastic products worths your choice, please feel free to contact us: easylock#rokist.com (replace "#" with "@")

What Do the Numbers in Recycling Triangles on Plastic Mean?

There are various plastic types in our everyday use. Different plastic types have different usage scenario, some are used for food storing, some for food packaging and even some are used as outdoor plastic pipes. You can identify which type of plastic it is by checking the number on the bottom of your plastic products. The number indicates how the products can be recycled. Let's see the 7 plastic types one by one.

Type Number 1 - PET

Type number 1 plastics are known as PETE or PET. It's made of polyethylene terephthalate. You can find PET plastic everywhere in our daily life, such as medicine containers, peanut butter containers, salad dressing and mouthwash bottles. It's the easiest plastic to be recycled and is widely accepted by recycling facilities and have a high demand from re-manufacturers.

Type Number 2 - HDPE
The second plastic types are HDPE, short for high-density polyethylene. It's mainly used in shampoo bottles, yogurt containers, butter containers and motor oil bottles. Type 2 plastics can be re-manufactured into toys, picnic tables, plastic rope and more.

Type Number 3 - PVC
The third one is PVC, also known as polyvinyl chloride. It's mainly associated with PVC pipes for home projects. Shower curtains, baby bottles nipples, clear bottles and more are made of recycled PVC. This one is difficult to be recycled.

Type Number 4 - LDPE
LDPE is short for low-density polyethylene. Grocery bags, sandwich bags, carpet and squeezable bottles are all made of LDPE. This one is difficult to be recycled as well and most of plastic pollution is especially because of the LDPE plastic shopping bags we use. To decrease the number of LDPE shopping bags and encouraging people to use reusable tote bags while shopping, many governments have released the bans on free plastic bags.

Type Number 5 - PP
Polypropylene (PP plastic) is frequently known as the material of producing food storage containers, ketchup and syrup bottles, plastic bottle caps, ice scrapers, bins and trays. It's difficult to recycle but it's durable and heat-resistant. You buy a plastic food storage containers, you can use it for years.

Type Number 6 - PS
Type number 6 is made from polystyrene, also known as PS and Styrofoam. Coffee cups, disposable plates and cutlery, egg cartons, meat trays and carryout containers are all PS plastic products.

Type Number 7 - Others
Type 7 plastics are labeled in Others categories because these plastics are made from a combination of plastics or the plastic materials that does not fall under any of that mentioned above. This plastics includes bullet-proof materials, DVDs, computer and MP3 player cases.

Different plastics have different features. Some are safe in the microwave and some are not. In these two articles, we've shown you which food containers are safe in microwave and how to choose dishwasher-safe plastic food containers.