Scientific molding is a disciplined, systematic approach to part processing based on what takes place during injection molding. The focus is based on controlling what happens to the material melt, and is defined by managing the viscosity of the material.

Benefits of this Approach

Defect Prevention: Consistent part quality based on understanding polymer rheological behavior.

Controlled Process: Based on hard data, not "black magic".

Part Discrimination: The process of knowing the part is good or defective in real time. Allows us to segregate suspect parts as molded, providing true process control.

Scheduling Flexibility: Allows us to produce parts of consistent quality, regardless of the molding machine. Process parameters are derived from the plastic’s variables, not machine variables.

Successful Plastics Application

These key components are building blocks for successful plastic applications. Unless they all follow the scientific molding process your program may not do well.

• Part design
• Tool design and construction
• Material selection and handling
• Processing

Process Control Objectives

Control of Key Plastic Processing Variables: A machine-independent procedure that provides four basic parameters to optimize the molding process.

• Plastic Temperature: We measure the temperature of the plastic– not barrel temperature.
• Velocity of injection (viscosity or flow rate): The objective is to push the same amount of material at the same rate during each machine cycle. Viscosity changes as the flow rate changes, and vice versa. Whenever the viscosity changes, the parts will vary. The greater control there is over material viscosity, the easier it is to have a consistent molding process and part quality.
• Plastic pressure: Measure and monitoring of cavity pressure, hydraulic pressure, and pack and hold pressures.
• Tool Temperature: We monitor cooling by measuring the coolant temperature inside and outside of the tool. We may also measure the mold temperature by another method.

Controlling these variables enables Empire Precision to have a locked process, and run the same cycle, shift after shift.

Scientific Molding Process

1. We correlate good parts with process measurements and then lock in the process. We then use data derived from pressure transducers inside the cavities to activate part segregation.
2. We perform a rheology study (study of flow and deformation of matter) with a series of short shots. Data from these shots is applied to derive a rheology curve, which is used to establish optimum velocity for the first-stage injection. This velocity assures we use the best possible viscosity for this mold.
3. We achieve mold optimization by thoroughly analyzing injection pressure, injection velocity, transfer position, fill time, pack, and hold pressure. We then conduct a gate seal study to determine pack time.
4. Once the process is stabilized, and acceptable parts are produced, we record basis data for the mold using Empire's Precision’s Proprietary Process Analysis Program. Processes are specific to the mold, not the machine.

These four steps become the “locked process” for every mold we build, and correlate to the parts submitted to the customer for approval