Tooling

Molding components using JERtech® thermoplastic biocomposites. Photo courtesy of Baytech Plastics (Ontario).

• The runner system should have a good flow path with minimal obstruction to minimize shearing of the thermoplastic biocomposite as it flows to the mold.
• Gates should be relatively large if the mold permits. Too small of gates will cause excess shear and may cause burning and/or discoloration of the molded component, as well as a polymer-rich appearance at the gate entrance.
• Use of direct gating into the thick section of the molded component is preferred. Use of an edge gate which is at least 2/3 the thickness of the wall stock through which the material is being gated is also acceptable. Note that ideal gate dimensions and location(s) will vary based on the wall stock and design of the molded component.
• Gate location(s) should be placed to minimize joining of flow fronts, as the thermoplastic biocomposite material is relatively knit line sensitive. Molded components may fracture more easily at joining flow fronts.
• Molded components with thick walls are preferred for injection-molding grades of JER's thermoplastic biocomposite.

Molding Tips

JERtech® compounds can be effectively molded at lower temperature profiles than pure polymers or other filled polymer composites. Photo courtesy of Baytech Plastics (Ontario).

• Drying: Maximum moisture content should be 0.30%. For pre-drying, we suggest one to three hours at 88° - 93°C (190° - 200°F) using hot air or one hour at 88° - 93°C (190° - 200°F) using a dessicant dryer.
• Nozzle Tip: the nozzle tip should have an orifice as close as possible to the diameter of the sprue to reduce the possibility of shearing. Tips that are too small will increase shear as well as contribute to potential discoloration by overheating of material as it enters the mold casing.
• Temperature Profile: process at lower temperature profile than with pure polymers or polymer blends. Recommended temperatature ranges are as follows:
  1. Rear zone: 340° to 370°F (171° to 188°C)
  2. Middle zone: 360° to 390°F (182° to 199°C)
  3. Front zone: 380° to 410°F (193° to 210°C)
  4. Nozzle tip: 390° to 410°F (199° to 210°C)

• Injection Pressure: minimal injection pressure is required to fill molds. Injection pressure will vary based on runner system and gates, as well as the design and thickness of the molded component.
• Back Pressure: minimal back pressure is required due to the flow characteristics of the thermoplastic biocomposite. Too high of back pressure may cause excess shear heat within the barrel, causing discoloration of the material.
• Fill Speed: JER's compounds are shear sensitive and best results are obtained when using slow to moderate fill speed. If the fill is too fast, a resin-rich polymer streaking condition may appear on the surface of the molded component.
• Hold Time: The thermoplastic biocomposite tends to set up quickly as the heat dissipates within the mold, allowing the component to be ejected sooner. This enables a shorter cycle time - which means more parts per hour and reduced costs!