Using multi-cavity molds that enable the manufacturing of many parts from one shot can enhance throughput and minimize part costs.
Do you know?
Production volume is also significantly improved by 200 percent to 700 percent when switching from single-cavity to multi-cavity molds.
While switching to multi-cavity tooling, some accessories used in single-cavity molds are expected to perform the same way in multiple cavities without some slight adjustments.
What will you learn in this blog?
This blog will discuss implementing quality in parts to achieve and sustain high production efficiency. By following these tips, you can build on essential tips that can help you quickly achieve good results in multi-cavity molding in the future.
Top Tips to Enhance Efficiency and Quality in Multi-Cavity Molds
Multi-cavity molds are very sophisticated and are characterized by complicated features. Transitional changes from single-cavity to multi-cavity molds can significantly impact production rates and cut expenses. Still, such transitions call for proper preparation and transition planning. Here are tips for overcoming these challenges and optimizing your multi-cavity molding process:
Adjust the Gates
Figure 2: Multi-Cavity Mold Gate Diagram
Some gates regulate the passage of the plastic material from when it enters the machine to when it starts to cool and is ejected out. It is recommended to apply tab or edge gates since this can contribute to the flexibility that is valuable in multi-cavity molds. Tab gates assist in limiting or countering stress on the tabbed area during ejection. Production expectations curbing the location and placement of gates vary depending on the expectations of a given firm. Knowing these expectations from the beginning of a project can keep redesign and issues at bay.
Hot runner valve gates can also be used to control mold imbalances in multi-cavity molds. They close the pathways to the fast-filling cavities, preventing flashing or overpacking while leaving the slow-filling cavities open. An option that costs less than the Parker valve is a flow control valve system regulated by a wormgear assembly. The molders can then control each nozzle’s flow by twisting a dial. The flow is unchangeable once it is set because its characteristic is permanence.
The other possible approach is real-time, closed-loop process control at each gate of the mold. This helps to attain faster startups, easy mold changes, and improved reject rates due to the setting up of a pressure and time profile of every drop location, the fill and packing rates, and the pressure gradient. The nozzle pressures are adjusted with the help of pressure sensors to achieve equal pressure throughout the filling cycle.
Design for Wall Thickness
The wall thickness level needs to be controlled to avoid stress marks so that components have the required minimum thickness in the wall and necessary matching features on adjacent parts. The gate area is subjected to high injection pressure, and if the wall is thin, it restricts the pressure.
Uneven thickness of the gates and wall results in shearing, flashing, and mold damage. Measures are increasing the wall thickness in the region of the gate, decreasing the injection pressure, or both.
Consider Side-Actions and Pickouts
The side actions and pickouts should be given much attention during the design stages. Side actions might be applicable for single-cavity molds and might not be permitted for multi-cavity tools in some cases. The pick-ups or the inserts that are manually loaded also depend on the part being designed and, therefore, must be well considered.
Use Sensor-Based Technologies
Cavity pressure sensing technology is used to prevent flow variation in filling more than one cavity at a time. Sensors can furnish flow pressure and cause imbalance. After an imbalance has been noticed, cavity pressure can be solved by sensing, which can be solved by using injection at low velocity to produce uniform pressures. This technology gives the full picture of how pressure is built during mold filling and assists in pressure control of imbalance problems.
Figure 3: Sensor-Based Technology
Optimize Cooling Channels
Cavity cooling is an essential factor that should be observed, especially in multi-cavity molds. Cooling channels should be designed to provide even cooling to all, preventing the part’s base from warping and maintaining each component’s quality. A better type of cooling can be conformal cooling channels, which tend to have paths along the contour of the part.
Balance the Fill Rate
This indicates that the fill rate of all the cavities should be balanced so that defects do not compromise the quality of the part. This can be done by designing the runner system so that the plastic is distributed evenly to each cavity, utilizing the simulation software to predict how the plastic will flow, and making corrections in the required mold design stage.
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Implement Advanced Simulation Software
Limiting the usage of simulation software offers the opportunity to design the mold and see how the molten plastic flows within it before the actual manufacturing process starts. From this, you learn problems like balance or pressure drop, which can be addressed in the mold design, runner system, and gating system before production.
Maintain Mold Precision
To minimize these problems, such as flashing, warping, or misalignment, it is required to keep the mold neat and machined very accurately to ensure that the tolerance of the mold is according to requirements. To reduce mold drift and achieve longer mold life, careful mold cleanliness and proper pickling or finishing should be performed in addition to high-precision machining.
Optimize Ejection Mechanisms
Selecting or designing ejection mechanisms demands particular concern as it involves providing equal ejection pressures for all the cavities to eject the parts quickly. It may be wise to use synchronized ejection systems whereby all or individual ejectors discharge or shoot parts simultaneously and do not distort or damage them.
Utilize High-Quality Materials
The selection of high material quality for the mold and the injected parts makes a big difference on the mold and the injected parts. Thus, using high-thermal-conductivity materials, wear resistance, and stability to support production and create high-quality parts is recommended.
Figure 4: High-Quality Material For Molds
Monitor Process Parameters
Some process controls that must be done continuously include temperature, pressure, and injection speed, among others. Successful part monitoring enables one to monitor and eliminate the variability in the system regarding the ideal process parameters that lead to part production and thus minimize defects.
Wrap Up
Effective gate systems, control of wall thickness, monitoring and controlling the system through sensor-based technology, and the use of simulation software can improve the productivity and product quality of multi-cavity molds. Following the above tips, you can achieve maximum efficiency and improve molding quality.
We at Go4mould offer all kinds of molds and ensure that all molding needs are met. Let our professionalism and commitment to quality translate into a better production line and the highest quality of your parts. Contact us for more details.
