Category: Fundamentals

Torsten’s Training Tip: Gate Seal Time

Gate seal time is an important aspect of the packing phase that needs to be understood to produce high quality molded parts.  Setting proper gate seal time plays a key role in packing parts. Properly packed parts will have even internal polymer molecular structure, fewer volumetric shrinkage differences, optimized part dimensions, and fewer sink marks […]

Torsten’s Training Tip: Thermal Pins

Designing thermally optimized molds becomes more challenging as part designs become more complex. There are various cooling design strategies, from using drilled coolant circuits or baffles and bubblers, to selecting mold steels or thermal pins (sometimes called heat pipes or heat tubes.) Thermal pins are a cooling strategy to optimize thermal behavior inside a mold. […]

Torsten’s Training Tip: Cashew Gates

Injection molded part quality is highly dependent on gate designs, sizes, and location. Because cashew gates, also called banana gates, can be placed in areas that are not visible, they are an option for molded parts that require perfect surface quality. Cashew gates, or banana gates, are sub-gates that are automatically de-gated and can be […]

Torsten’s Training Tip: Mold Steel Selection

Injection molds are designed and built to allow parts to be produced from various polymers and to be utilized for a variety of applications. A mold design team must possess the ability to evaluate and determine the optimal mold steel for each mold component to effectively produce high quality plastic parts. How do mold designers […]

Torsten’s Training Tip: Deformation Behavior and Reversing PVT Curves

Plastic part designers have an abundance of polymer materials to choose from, ranging from commodity to technical or engineered polymers. Selecting the optimal material for each design is key to a successful molding project. Polymer materials must be heated to their melt temperature ranges to be injection molded. Polymer strength, stiffness, and deformation behavior are […]

Torsten’s Training Tips: Warpage Due to Fiber Orientation

Fiber orientation plays a significant role in the shrinkage and warpage of a molded part. Let’s look at why. Fiber -filled composite plastic materials will induce anisotropic mechanical properties. Fiber reinforced parts have directional mechanical properties that are stronger in the direction (or parallel) to the flow and weaker transverse (or perpendicular) to the flow. […]

Torsten’s Training Tips: Understanding Shrinkage and Warpage Behaviors

Minimizing volumetric shrinkages and reducing part warpage are important considerations when designing injection molded parts. By understanding the interaction of part and mold designs, polymer material, and the molding process, preventative measures can be designed into the molding system to minimize shrinkage and warpage. Polymer materials naturally expand when they are heated and shrink as […]

Torsten’s Training Tips: PVT

The Pressure-Volume-Temperature (or PVT) relationship of different materials is a calculation of the compressibility of material during the packing and cooling phase. Since this affects a parts’ shrinkage and warpage after ejection, having a clear understanding of PVT is essential for success. Polymer material shrinkage inside a mold must be compensated for with packing and […]

Torsten’s Training Tips: Mold Design — Pin-Point Gates

Gate placement is an important aspect of mold design to achieve optimal part quality. Let’s look at some advantages and disadvantages to using pin-point (pinpoint) gates in mold design. Because gate placement options are often limited by design restrictions and other part-related constraints, understanding and utilizing industry best-practices can be helpful in achieving the desired […]

Torsten’s Training Tips: Packing Pressure Profiles (Amorphous and Semi-Crystalline Materials)

One of the key steps in the injection molding process is the packing and holding phase, sometimes also referred to as the compensation phase. During the packing phase material is continuously “packed” into a cavity, thereby compensating for the shrinkage that occurs due to material cooling inside the mold. To optimize a packing profile, it […]