Since 1950, injection molding has been used worldwide as a method of producing plastic parts. It is the most economical method for producing extremely large quantities of the same type of part in a short period of time. Most plastics produced today are divided into three categories based on their main characteristics.
Thermoplastics liquefy when they reach a certain temperature and take on a solid form when they cool down. This process can be repeated. Thermosetting plastics change their chemical composition when heated. The shape they assume upon cooling cannot be changed upon reheating. They are destroyed at a certain temperature but prove to be very stable until then. Elastomers have the property of deforming under pressure or tension at room temperature and returning to their original shape only when the force is removed.
Plastics for Injection Molding
In the more than 20 years we have been active in the injection molding industry in nearby California, Texas, there have been many changes in the development of plastics. Thousands of new plastics and compounds have been created, all of which have different injection molding capabilities and have found their applications accordingly. Most of them, however, have been developed for very specific technical applications. Many plastics have properties similar to those of already known compounds. Therefore, despite all the new developments, the number of materials we inject mold remains manageable. The injection molding companies working on the development of new plastics are a big exception. This work is being done mainly at universities. However, there are also very successful specialists who develop plastics directly for a specific need and can be described as contract developers. Over the years, trends can be observed that influence the distribution of materials across applications. There are always factors according to which plastic is selected for technical and industrial use.
Many Plastics Are Considered for Injection Molding
There are various data collections that list commercially available plastics. Currently, there are almost 90,000 different types and names! These are the ones we are aiming at. This huge number of plastics can be grouped into about 45 polymer groups, which in turn can be divided into two main categories: thermosets and thermoplastics. In addition, there are elastomers, which, like natural rubber, are more commonly used in tires and rubber bands, for example. Historically, the early development of thermosets as the first plastics led to their early dominance as the main group for injection molding. At the same time, however, the possibilities for thermoplastics have expanded to such an extent that they now account for approximately 85% of commercial production. A brief reminder of the basic differences between thermosets and thermoplastics. Once thermoset plastics are mixed together and cured, they retain their shape. This curing is triggered by a chemical catalyst or high heat.
TX Molds Injection Molding & Tooling
We also plan and produce for your industry and company. Send us your inquiry or give us a call. We are happy to help you.
Basic Conditions for Choosing the Right Plastic Material
Of course, choosing the right material for your injection molding is usually based on the properties that the injection molded part will exhibit later in its life. The following properties play a role and need to be carefully considered.
- Plasticity of the molded plastic part after injection molding
Does the molded part still have a certain degree of plasticity after production? (Thermoplastics)
- Elasticity of plastic
To what extent must the part return to its original shape when the compression or tension force is reduced? (Elastomer)
- Hardness of plastics
How should the material react under different levels of force? (Particularly hard: thermosetting materials)
- Fracture strength of plastics
To what extent must a material withstand the force acting on it before it exceeds its glass transition point, i.e., fracture?
- Temperature resistance of plastics
To what temperature will the finished part be exposed and how long must it withstand without changing its properties?
- Heat deflection temperature of plastics
This subset of temperature resistance focuses on maintaining shape at high or low temperatures.
- Chemical resistance of plastics
In many applications of plastics, their reaction with acids, bases, oils, or salts is also decisive.
With all these considerations, there is of course another important issue to keep in mind. Every plastic product has its price. The rarer the plastic to be used, with special capabilities and properties, the higher this price is naturally going to be. As a supplier of injection molding services, we at TX MOLD work strictly on the principle of maximum economic efficiency.
Thermoplastics, Such As PP, PE, ABS, and PS, Make Up the Majority of
It goes without saying that considering the properties of thermoplastics, i.e. that the material can be remelted any number of times and can take on new shapes as it cools, it offers greater scope for production in injection molding. In addition, thermoplastics can be welded as a material after injection molding. But let’s leave the issue of variety aside. In terms of hard numbers, plastic injection molding in the world is limited to four main materials.
Less than half of all injection molded parts produced each year are made of polypropylene (40%), acrylonitrile-butadiene-styrene (30%), polyethylene (15%), and polystyrene (10%). Acrylonitrile-butadiene-styrene is known by many as ABS for short. The subcategories ABS-ESD and ABS-FR are used primarily in the automotive and electrical industries for their high stability to pressure and tension, their ability to be free of static electricity, and their high fire resistance.
Would you like to learn more about TX MOLD injection molding? Please contact us. We would be happy to inform you about our products and possibilities.