What is shrinkage and warpage?

Shrinkage is defined as a change in size. Warpage is a change in shape.

What is metering stroke in injection molding?

Metering section, which generally makes up 25% of the flight length (five flights). The purpose of the metering section is to pump plastic forward through the check valve, developing the pressure to counteract the back pressure to push the screw backwards to develop the shot size.

How is shrinkage value calculated?

Subtract the final size from the original size to find the amount of the shrinkage. For example, if a felt square shrinks from 8 square inches to 6 square inches, subtract 6 from 8, resulting in 2 square inches of shrinkage. Divide the amount of shrinkage by the original size to find the shrinkage rate.

What causes shrinkage in injection Moulding?

Shrinkage occurs at a molecular level when plastics melt and cool. Volumetric shrinkage is caused by thermal contraction, which affects all polymers (semi-crystalline and amorphous), and influences how the material changes in volume as it transitions from a liquid to a solid.

What is unit of injection?

The injection unit of injection molding machine is much like an extruder. The injection unit melts the polymer resin and injects the polymer melt into the mold. It consists of a barrel that is fed from one end by a hopper containing a supply of plastic pellets. The unit may be: ram fed or screw fed.

What does full platen mean?

In office copiers and scanners, the platen is a flat glass surface on which operators place papers or books for scanning. The platen is also called the flatbed. Platens are also used in some printers, such as the dot-matrix printer.

How do you calculate tonnage for injection molding?

Now you can calculate necessary tonnage based on the projected area times the clamp factor for the material used. T = A x cf. For example, the projected area of the molded part is 150 sq/in times a clamp factor of 3 (tonnage needed/square inch from material data sheet). 150 x 3 = 450 tons needed.

What is Makrolon mg plate?

Makrolon® MG. Makrolon® MG (machine grade) polycarbonate engineering plate is an amorphous thermoplastic material that offers extremely high impact strength, high modulus of elasticity, outstanding dimensional stability and good mechanical and electrical properties.

What are Makrolon® resins?

The broad portfolio of Makrolon® polycarbonate resins from Covestro includes general purpose, lighting, medical and food contact, flame-retardant, impact-modified and glass-fiber reinforced grades, which can be used for injection molding, extrusion and blow molding.

What is the electrical resistance of Makrolon®?

• Electrical insulation Volume resistivity 1014Ω · m; Dielectric strength up to 36 kV/mm (1 mm thickness) All Makrolon® batches are homogenized after production. The production plants for Makrolon® have been certified to DIN EN ISO 9001 and 14001 by the appropiate certification organizations.

What is polycarbonate (Makrolon®)?

Polycarbonate (Makrolon® / Lexan®) is a transparent thermoplastic sheet material used where impact resistance, flame retardency, good dielectric properties and optical clarity are priorities.