Top 3 mistakes to avoid when ordering custom injection molded parts

Injection molded parts find broad applications in different sectors around the globe due to their efficiency as well as accuracy in producing mass parts. Despite the ease in mass production and precision of parts with injection molding processes, some customers often make common mistakes during the customization of parts due to inadequate knowledge about the injection molding process. This always results in extra costs, reduced quality of products, and at times, delayed delivery. In this article, we discuss the three major mistakes that you should avoid when making an order for custom injection molded parts. By following this, you will be able to streamline the design process and ensure that your project is on track.

I. Ignoring detail optimization in the design stage

Detail optimization in the design stage is critical for customizing injection molded parts. Most customers concentrate exclusively on product appearance and function in the early design stage and neglect the peculiar requirements of the injection molding process. The following key aspects need emphasis in the design stage:

1. Wall thickness uniformity and draft angle

Neglect of wall thickness uniformity results in stress concentration in the part during cooling, therefore shrinkage, warping, and problems related to those two will be observed; neglect of the standard draft angle will cause the plastic injection mold to remain on the mold inseparable or even damage the mold. The design should provide uniform wall thickness, avoid sharp variations in thickness, and specify an adequate draft angle (typically 1° to 2°) based on material shrinkage and part geometry.

2. Position of parting line

The position of the parting line has its direct influence on the appearance as well as the function of the part. If this is not rightfully done, it could leave some obvious marks on the surface of the part; therefore, affecting the appearance and performance. In design, the parting line should be placed in non-critical areas as much as possible.

3. Design for manufacturability (DFM)

Manufacturability is the key consideration in the design of injection molded parts. Close cooperation with the mold manufacturer, involving them at an early stage of design to optimize and develop the tooling, will result in reduced production costs and better quality parts. Such design thinking goes a long way in not only eliminating problems in production but also allows much leeway for subsequent modifications and optimizations.

II. Incorrect material selection

Material selection is a vital factor in the injection molding process while most customers select materials based on past experiences or merely on cost prices, overlooking key aspects such as mechanical properties, chemical resistance, and qualities in molding. The following are some aspects to consider in the selection of materials:

1. Mechanical properties and chemical resistance

Some plastics degrade when exposed to high temperatures, others do not meet the required strength or wear resistance. Where the part is to be used in a corrosive environment, its material should be chemical resistant.
An instance is PP, which tolerates most chemicals, and PS, which is attacked by chemical corrosion. The choice of material should comprehensively consider the working environment and the performance requirements of the part.

2. Molding characteristics

Material properties such as flow, shrinkage, and thermal stability are the more direct parameters that would influence the injection molding process conditions and quality of molded parts. For instance, polycarbonate is not only strong and clear, but often too of low fluidity, requiring high injection pressure.

III. Ignoring mold costs, time, and post-processing requirements

Most clients do not realize how costly and time-consuming plastic injection mold manufacturing can be, nor do they consider post-processing needs. As a result, they face project delays or receive parts that do not meet final requirements. The most common issues include:

1.Costs and time of molding

The making of molds is long and tricky since one has to do accurate machining, heat treatment, and surface treatment. All these add up to the cost and time but will enhance the quality of the mold and also its lifespan. Prior to commencing, speak with the mold maker to learn about the process and explore using fast mold technology, like aluminum molds, to reduce delivery time. This way can speed up getting to market and lower the risks in producing large volumes.

2. Post-making needs

Parts made by injection molding normally need extra work done on them, like cleaning, painting, adding a metal layer, or putting parts together. Not thinking about these needs at the start can lead to parts that don’t work for the final goal. For instance, not enough room for cleaning can harm parts, the wrong surface texture can cause painting problems, and bad fitting sizes can stop assembly. Sort out extra work needs at the design phase and work with partners to check if it can be done and is smart to do, saving time and money in the end.

IV. Conclusion

Customizing injection molded parts becomes majorly a task that is highly specialized and complex. It ensures the major three mistakes above are not in the picture, then for sure you will get a project through the success ramp, reduce costs, shorten delivery time and optimizing design, material selection, and supplier cooperation are key links. I can only wish this article will bring great inspiration to you and have you succeed in the field of plastic injection mold.