A surprising number of projects are completed without using a prototype tool. The general idea is that prototype tooling is an extra, unnecessary step that increases cost and decreases development and production times.
Actually, the opposite is true. Custom injection molding done without a prototype tool typically leads to a series of required production tool adjustments that are both costly and disruptive. The perceived savings of skipping prototype tooling quickly evaporate, and the higher risk of part defect introduces the possibility of incurring legal expenses and other related costs.
Depending on the complexity of the application, prototype tooling generally accounts for about 20-40% of overall production tooling costs. It's not an insignificant investment, but one that's well worth it when you consider the advantages.
Injection molding tooling is at the heart of injection molding. Whether it’s a complex application or simple part, plastic injection tooling – more specifically, tooling design – determines the quality of the injection molding process and the parts produced.
Success in the injection molding business isn’t limited to having the right equipment or the latest technologies. It's a good start, of course, but it takes more to meet the needs of customers that require custom injection molding for complex applications completed under challenging time and cost constraints.
Custom injection molders must have top toolmakers in their supply chains that prioritize manufacturing excellence and customer service. Core to this philosophy is that toolmakers must treat the injection molders’ customers as their own.
Prototyping an injection-molded component is necessary to ensure proper quality and performance. Rapid tool prototyping and prototyping for injection molding production are two standard prototyping options, and each has its own advantages — but which is right for your projects?
Custom injection molding projects are, by nature, an expensive undertaking. Part development and tooling design/build often account for the majority of the budget, particularly in the case of intricate components. The consistency, quality, and cost of the part produced largely hinge on optimizing these two aspects of the project. Missteps can lead to expensive setbacks, product defects, and lower profits.
Custom injection molding projects are understandably focused on plastics selection. After all, the materials used to construct the parts have the greatest influence over quality and performance.
However, the grade of injection molding tool steel chosen for production also has a major impact on project outcomes. Cycle times, part criteria, production volume, cost, and maintenance expectations all must be factored in to align the steel with the need.
Insert injection molding is a process that requires an insert — typically metal — to be pre-placed in the tool for injected plastic to flow around. Encapsulating the metal insert with plastic creates a single molded plastic piece that’s generally stronger than one created using secondary assembly.
Insert molding can be accomplished through two methods:
- Manual metal insert loading: The generally more cost-effective way to approach very low-volume applications or extremely complex part geometries
- Automated metal insert molding: A better choice for part consistency. It minimizes human error, improves efficiencies, and ensures optimal cycle times.
Securing an insert in plastic requires precision and a thorough knowledge of how each individual substrate reacts to conditions during the injection molding process.
Let's begin with the basics: What is GD&T, and why is it important for injection molded parts? Geometric dimensioning and tolerancing (GD&T) is a symbolic language that is used on engineering drawings and computer-generated models.
GD&T communicates geometric dimensions and allowable tolerances for various parts. Not only is this a useful exercise for product design, it’s also helpful on the manufacturing floor because engineers and operators can quickly see the degree of tolerance that is required for each part.
Surface finish for plastic parts can vary a great deal, depending on the physical and chemical properties of the polymer blend as well as the parameters of the injection molding process.
A custom injection molder works with the customer to determine how important the injection molding surface finish is to the final product's appearance and/or performance. For example, does the product need to be eye-catching or simply functional? Depending on the answer, the material selected and the desired finish will determine the settings for the injection molding process and any required secondary finishing operations.