How to choose an electric injection molding machine suitable for producing thick-walled parts?

electric injection molding machine

2026/04/07 By le zhan

Thick-walled parts may seem easier to mold than thin-walled parts because the cavity requires a lower filling speed. However, they actually place different demands on electric injection molding machines. They require stable communication response speeds, highly repeatable injection behavior, longer holding pressure times, and precise low-speed control. Problems in any of these areas can lead to quality issues such as shrinkage marks, voids, inconsistent shrinkage, and flow marks. So, choosing the right electric injection molding machine for thick-walled part production is crucial, ensuring the machine’s control system is matched to the material and the part’s actual characteristics. Topstar electric injection molding machines, with their ultra-fast communication response, discrete intelligent drives, long-term pressure maintenance, and precise ultra-low-speed injection control, are particularly well-suited for the production of thick-walled parts.

What are the requirements for electric injection molding machine for thick-walled parts?

The production of thick-walled parts requires precise process timing control. Although the mold filling speed may be slower than for thin-walled parts, the injection molding machine must still respond immediately to process changes. Communication delays between the controller and drive system affect the transition from filling to holding pressure, thereby impacting final product quality.

When selecting an electric injection molding machine, communication response is one of the primary evaluation criteria. In the production of thick-walled parts, the electric injection molding machine must quickly detect and respond to process signals to maintain a stable melt state. If the controller response is too slow, the machine may lose the precise pressure window needed to compensate for shrinkage, resulting in sink marks or internal voids, defects that are difficult to repair later. A fast-responding electric injection molding machine improves process stability and reduces potential delays accumulated over long production cycles.

Injection Repeatability Accuracy in Electric Injection Molding Machine

Thick-walled parts may still seem to have lower requirements than thin-walled parts, because the material is under pressure for a longer time. The shrinkage process is slower, and thick-walled parts are often more sensitive to deviations in the injection process. If the machine cannot accurately repeat its movements, part consistency will be affected.

Repeatability accuracy is also important when evaluating an electric injection molding machine. Topstar electric injection molding machines achieve an injection repeatability accuracy of ±0.01 mm. This accuracy helps ensure that each cycle starts from the same mechanical position and follows the same control logic, as thick-walled parts amplify process deviations. Even minute variations in movement can alter the pressure distribution within the mold cavity. Tiny positional deviations can affect shrinkage compensation. Repeatability minimizes these risks. When the machine operates consistently in each cycle, repeatability also helps document the process more effectively.

Choice of Holding Pressure Time

The production of thick-walled parts requires longer holding pressure times. The melt within the cavity cools slowly, and the shrinkage duration is longer than for thin-walled parts. If the holding time ends prematurely, the cavity cannot fully compensate for the shrinkage, often resulting in sink marks, internal voids, or dimensional instability.

Therefore, the ability to hold pressure for extended periods is one of the characteristics used to evaluate whether an electric injection molding machine is suitable for producing both thick and thin parts. Machines designed for long holding times provide sufficient support for the melt during the critical solidification phase. Topstar’s electric injection molding machines utilize custom high-load modules, enabling maximum holding times of up to 30 minutes. This is a significant advantage for the production of thick-walled parts, as it provides ample time to compensate for shrinkage and maintain surface quality. It also reduces the number of parts scrapped due to sink marks or voids, thereby increasing yield.

Precise Low-Speed Control

Thick-walled parts do not require constant, rapid filling, but precise control of the filling speed is essential. If the injection speed is too fast, flow marks may form in the melt, causing uneven material mixing. If the injection speed is too inconsistent, deviations in the surface appearance or internal structure of the parts may occur.

When selecting an electric injection molding machine, ensure it has a low-speed control range. A good molding machine should maintain a stable injection speed even at extremely low injection speeds. Topstar’s precision injection technology on electric injection molding machines enables injection speed control as low as 0.1 mm/s, resulting in highly controllable processes during the critical filling stage. Through precise low-speed motion control, the machine helps the material flow smoothly and evenly through the cavity, resulting in cleaner surfaces and more uniform quality in thick-walled parts.

Why is Topstar’s Electric IMM technology suitable for thick-walled parts production?

Topstar’s electric injection molding machines employ a discrete intelligent drive system, one of the core reasons for their superior performance in thick-walled applications. It integrates drive and control functions, creating a faster and more direct response path. This resulted in a communication response time of just 0.125 milliseconds, enabling the machine to react instantly to changes in the process.

The machining of thick-walled parts relies on precise coordination between the filling and holding pressure phases. If the machine response time is too long, the pressure window may shift, reducing the efficiency of the compensation process. Topstar’s discrete intelligent drive system eliminates this problem by reducing system-level latency. Faster response times lead to smoother control, more stable process transitions, and better synchronization with mold and material properties.

Thick-walled household appliance injection molded parts

Customized High-Load Module

Long holding pressure is a key reason why many machines begin to lose their edge. Some injection molding machines perform well during filling but cannot maintain pressure long enough to compensate for shrinkage. Topstar’s customized high-load module allows electric injection molding machines to maintain holding pressure for up to 30 minutes. During this time, the cavity is continuously supported by pressure while the melt cools and shrinks. This reduces the risk of shrinkage marks, voids, and dimensional instability. From a product perspective, this capability results in more consistent yields and fewer defects. From a management perspective, this means higher yields and more predictable production planning. The high-load modular design provides the machine with the durability needed to meet this requirement consistently.

Ultra-Low Speed Precision Control Electric Injection Molding Machine

Thick-walled parts may not require the fastest filling speed, but they absolutely need the most consistent filling speed. Topstar’s ultra-low-speed precision injection control technology, combined with high-pressure, low-speed coordinated control, enables electric injection molding machines to control injection speed to 0.1 mm/s precisely.

This feature helps eliminate flow marks and color mixing that often occur due to uneven material flow. It also allows the machine to control better the early and late stages of cavity filling, where many surface and structural problems begin. For manufacturers producing high-quality thick-walled parts, this control significantly improves part appearance and process stability.

Fulfilling Four Key Capabilities

How should buyers make their final choice? First, assess whether the machine meets four key capabilities: Is the machine’s response speed fast enough? Is the repeatability high enough? Is the pressure hold time long enough? And is the low-speed control precise? If the answer to all four questions is yes, then this injection molding machine is ideal for producing thick-walled parts. Topstar’s electric injection molding machines meet these standards through discrete, intelligent drives, long-term pressure maintenance, and precise low-speed control, making them better suited for the production of thick-walled parts.

Prev: The Core Technology of Topstar Cartesian Coordinate Robots

Next: Not Next

How to choose an electric injection molding machine suitable for producing thick-walled parts?

What are the requirements for electric injection molding machine for thick-walled parts?