The Design Engineer’s Checklist For Injection Molding

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Injection molding is a common technique used to make plastic items and parts. The process involves melting plastic pellets at high temperatures and passing the molten plastic into a plastic injection mold through a nozzle. The finished product is ejected from the mold after proper cooling. The final shape of the product depends on the mold design.

This process is used for everything from making consumer goods to industrial products. But even the most simple-looking injection molding products require complex planning and design considerations. As a result, the mold design, raw material, and injection process are crucial in ensuring the products meet industry regulations.

This is why design engineers are required to design efficient injection molding processes while monitoring various parameters of the process to ensure the finished goods are of high quality and are free from any defects. These parameters include the product development stage, design stage, pre-production stage, and production stage, and even the slightest errors in these stages can lead to bigger problems during production. Learn about the process by reading our design engineer’s checklist guide.

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Product Development Stage

Functions Of The Product

The most important part of the product development stage is determining the functions of the product. This helps determine the product’s right features and mold design. Mold design is the most important part of the plastic injection molding process because the outcome of the finished goods depends on it.

End User Of The Product

A clear vision of the finished product will help facilitate the production process and reduce risk and errors. The design engineer should ideally have all the information regarding the product to help streamline the process as much as possible and apply effective cost-cutting measures. It will also help the engineer eliminate certain unrequired features from the finished product.

Market For The Product

The market selection of the product is important for the end user and the industry regulations. For example, a product for the automotive industry must meet industry regulations. These regulations include the color, type of material, thickness of the material, or any other specific design considerations.

Market Price Of The Product

The market price might not seem significant for the design engineer, but it’s quite significant. The final price of the finished product will determine the cost of the production stage. If the client plans on selling the product at a cheaper rate, but the production cost is high, it will not be feasible to facilitate the production on the client’s budget, even with extreme cost-cutting measures. On the other hand, the lower cost may compromise the product’s quality and lead to defects after production. Again, this will increase the cost as the defective products must be replaced.

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Product Design Stage

The Complexity Of The Product

The complicity of the product plays a huge role in the mold design and production process. A difficult mold design might require special material and design considerations. At the same time, complex resin products might take longer production cycles which will increase their cost. The complexity of the product also affects its functionality and acceptance in the market. These things can lead to lower sales.

Determine The Material

Before starting production, the right materials should be picked depending on the client’s requirements and the properties of the finished goods. Design engineers can choose plastic from ABS plastic, nylon, polypropylene, polyethylene, and many more options. Plastics are also chosen based on the design of the material, as certain plastics provide a better structure for thin-walled products.

Determination Of The Injection Molding Process

Different resins require different injection molding processes, such as thermal injection molding, gas-assisted injection molding, structural molding, and over-molding. The process selection largely depends on the resin and the properties of the finished product. This is why the engineer must determine the right process before starting production.

Picking The Color

Color considerations are more than just aesthetic choices for clients. They’re also required for industrial safety and regulatory reasons. Moreover, the plastic pellets are pre-colored. So finalizing the color before production allows the company to order the right raw materials and comply with regulatory laws.

Risk Calculation

Certain mold design requirements may possess a risk to the production process. For example, thinner walls are a bit difficult to mold. Similarly, squared corners, lack of internal support, lack of draft design, and lack of gussets are all risk factors the design engineer must consider. All these issues can affect the production process and the product’s final quality. Certain designs also affect the flow of the injection molding resin.

Pre-Production And Production Stages

Tolerances In Quality Control

Quality control processes are highly regulated to ensure the finished product meets the client’s requirements. However, there are certain tolerances given for minor issues. Before the production stage begins, the design engineer needs to determine the percentage of tolerance acceptable for the produced goods. This ensures that the quality control process is effective, efficient, and consistent.

Quantity Of The Product

If the production phase runs longer, the estimated cost of the product is lowered. But in some cases, longer production runs aren’t efficient and can increase the lead time in the order completion stage. The design engineer should determine if longer or lower production cycles benefit the client. Generally, lower production runs are more effective for products with fewer sales.

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