Metal To Plastics Conversion

The single most important benefit in metal to plastic conversion is cost savings with improved product quality. Let's consider the advantages to replacing metal casting with injection or insert molding.

1. Decrease Piece Part Prices (Top)
A penny saved is a penny earned. After initial tooling costs are paid, the piece part pricing is usually much less than the same part produced in metal, whether it be a stamping, casting, or a die cast part. This cost savings is realized because the injection molding process has faster cycle times (more parts made per machine hour) and these parts are identical from one to the other which eliminates secondary machining.

2.Eliminate Time-Consuming and Costly Secondary Operations (Top)
Eliminating secondary operations further reduces costs. Plastic material can be colored with color concentrates before molding - eliminating secondary painting operations. Injection molds can be textured or given various levels of polished surfaces before molding. The costly assembly of several metal stampings or castings fastened together can often be replaced by a single injection molded part incorporating the features of the total assembly. If multiple assemblies are required, the plastic parts can have snap-together features to eliminate any fasteners. Eliminating sub-assembly tooling or fixtures by using injection molded parts can quicken delivery in new product development programs.

3. Reduce Product Weight and Improve User Ease (Top)
One primary advantage of using plastics instead of metals is weight reduction. Reducing product weight with plastics gives you more parts per pound of material, significantly reduces shipping costs and improves the end-user's physical ease in utilizing the product.
A comparison of the specific gravity values of metals to plastics is shown in the following table:

METALS	PLASTICS
Aluminum 2.5 to 2.8 Brass 8.4 to 8.7 Copper 8.8 Zinc 6.9 to 7.2 Steels 7.7 to 7.83	Polycarbonate 1.2 to 1.4 Nylon(most types) 1.2 to 1.7 Polyethylene .92 to .95 Polypropylene .90 to 1.04 ABS 1.02 to 1.4

4. Gain Greater Product Structural Strength (Top)
That third little pig really knew how to choose the right materials to build a strong house. Choosing plastic over metal gives you products which are light-weight, easier to use and yet possess increased structural strength. Plastic parts can be stronger than metal parts through the use of engineering grade materials. In addition, the ability to mold in structural strength such as ribs, bosses and gussets when the part is originally produced instead of fastening, welding and gluing operations afterwards can affect the total strength of the assembled part as well as reduce additional costs.

5. Increase Your Product Design Options (Top)
Don't let the design limitations of metals trap you between a rock and a hard place. Increase your design options and requirements and still keep costs down. The area of greatest difference between metals and plastics is plastics' ease in producing complex shapes. The costly assembly of several metal stampings or castings fastened together can often be replaced by a single injection molded part incorporating the features of the total assembly. If multiple assemblies are required, the plastic parts can have snap-together features to eliminate any fasteners. Injection molded parts can shorten the time to the market place in new product development programs because of elimination of sub-assembly tooling or fixtures.
If heavy metal shakes, rattles and rolls, then plastic twists and shouts. Plastics are easily processed into complex shapes that would be impossible for metal because plastic materials have non-Newtonian flow behavior. This means that the viscosity (resistance to flow) will decrease when the flow rate increases. The flow rate is increased by increasing the injection pressures. The standard injection molding pressures are 20,000 to 30,000 Psi. This capability allows plastics to be made to flow to produce thin walled parts with uniform wall dimensions replacing the more costly thicker-walled design features of most metal parts.

6. Save Dollars by Re-Using Materials (Top)
Any way you look at it, recycling makes sense. Re-using materials by adding regrind (ground up runners and scrap parts) to virgin materials generates even more cost savings.
Plastic materials fall into two basic types of process groups: Thermoset and Thermoplastic. Thermoset (often called compression molding) is like working with epoxy. Once the material has been heated and formed in a mold, it is set. The material cannot again be processed; it is literally a reaction by temperature or thermally set. Examples of thermoset materials are Alkyd, Polyesters, Melamine and Phenolic. Most injection molding plastics are thermoplastics; that is they can be reprocessed. Thermoplastics fall into two distinctive molecular groups: amorphous and crystalline. Amorphous materials when processed act like honey; that is they never really melt, they just soften and are formed under pressure. Crystalline materials act like solder or ice. They have a specific melt temperature and remain a solid until this temperature is reached. After the melt temperature is achieved, the materials flow very easily with very low viscosities. When the material is cooled to a temperature below the melt temperature, the material hardens to a solid form.

Amorphous Materials	Crystalline Materials
Acrylic ABS Polystyrene PVC Polycarbonate	Nylon Polypropylene Acteal Polyester Polyethylene

Comparison Characteristics:

	Amorphous Materials	Crystalline Materials
Shrinkage	.004 - .012 in/in	.012 - .025/in/in
Ease of flow	relatively stiff flowing	easy above melting temperature
Dimensional control	easier to maintain	more difficult to maintain

7. Increase Product Life (Top)
The Tin Man needed more than a brain to last - he needed an endless supply of oil as well. Replace the environmental vulnerability of metals with the durability and longevity of plastics. Most plastic materials have greater chemical resistance than most metals. Plastics do not rust or oxidize as metals do and most are not affected, as are metals, by acids or base compounds.

Since 1949, Plastics One has specialized in the custom design, tooling, and injection and insert molding of products used in the medical, telecommunications, aerospace and consumer products industries. Our Engineering and Tooling divisions are staffed by designers and mold makers with the knowledge and computer-aided design experience to create the exact part for your needs. As molders, we specialize in custom injection molding and insert molding using a wide variety of engineering polymers, from thermoplastic elastomers to reinforced or filled resins. Shot sizes include 1/10 of a gram up to 79 ounces. In addition, we offer hot stamping, ultrasonic welding, and packaging services for your convenience.

METAL TO PLASTIC CONVERSION