Resin Identification Codes

What Are the Resin Identification Codes from SPI?
Resin Identification Codes were introduced in 1988 by SPI. SPI is now known as The Plastics Industry Trade Association (formerly Society of the Plastics Industry). The codes are intended to facilitate the sorting of similar looking plastics at recycling centers across the country. While there is no federal legislation or requirements to use these symbols, many states now mandate them. The Resin Identification Codes are a seven number system. … Read more

Resin Idendification Code

How to Make an Injection Mold

What is an Injection Mold?
An injection mold is a tool that when all the parts are assembled, fits into an injection molding machine to manufacture identical plastic parts. Injection molds start with a drawing by an engineer of the part required for an application. Next an engineer with knowledge of the injection mold making process makes a mold drawing.
How an Injection Mold is Made
Making an injection mold takes a great deal of skill and some very expensive machinery. … Read more

Injection Mold

What Kind of Plastic is This?

What Plastic is this Part  Made Of?
There are several ways to determine what plastic the object you have is made of:
*Plastic Resin Identification Codes
*Burn Test
*Floats or sinks in water
Plastic Resin Identification Codes
The plastics identification codes were developed in 1988 by SPI Society of Plastic Industries. These codes are intended to be recycling codes. #1 is polyethylene terephthalate (PETE, PET), #2 high density polyethylene (HDPE). #3 polyvinyl chloride (PVC), … Read more

what kind of plastic

UV Degradation of Plastics and UV Resistant Additives

Sunlight May Degrade Plastics
Many plastics will degrade in sunlight without the addition of light blockers, stabilizers or UV absorbers. Materials may discolor, crack or completely disintegrate. While the UV degradation of a polymer in sunlight is usually only .05 deep in the material’s surface the highly brittle nature of some plastics may lead to complete component failure.
Signs of UV Degradation
*Brittle outer layer (loss of tensile elongation)
*Reduction in molecular weight
*Loss in mechanical properties
*Change in chemical properties
*Discoloration, … Read more

UV degradation

Nylon Fasteners: Screws, Hex Nuts, Flat Washers and Nylon Custom Parts

Nylon 6/6 is a polyamide plastic made up of two monomers. Each monomer contains 6 carbon atoms of hexamethylenediamiine and adipic acid. We have written about the reasons not to use nylon in our blog some time ago.
Six Reasons Not to Use Nylon
Nylon is hygroscopic meaning is absorbs water even from the natural environment. This can cause changes in a part’s dimensions.
It is not UV resistant without additives.
It is not particularly chemically resistant as it performs poorly in acids and halogens. … Read more

Nyon plastic