When a company is considering injection molding, there are plenty of questions to answer before moving from a product concept to full-scale production. How does the process work? Which material is right for the part? How much will tooling and production cost? What should you expect from a manufacturing partner? How does injection molding work?
The answers depend on the part, material, tooling, production requirements, and intended application. The following guide covers some of the most common questions manufacturers ask when evaluating plastic injection molding.
What Are the Four Basic Stages of Injection Molding?
The injection molding procedure can be broken into four basic stages: clamping, injection, cooling, and ejection.
First, the mold is closed and clamped securely. Next, heated plastic is injected into the mold cavity under pressure. The material then cools and solidifies into the desired shape. Finally, the mold opens, and the finished part is ejected.
The cycle then begins again. While the basic process is straightforward, factors such as material properties, part design, tooling, and processing conditions all influence the finished component.
Why Is Injection Molding So Widely Used?
Injection molding is widely used because it can produce repeatable plastic components at production volumes that make the process practical for many applications. Once the tooling is developed, the same mold can be used repeatedly to produce consistent parts.
The process also accommodates a wide range of shapes and designs. Depending on the material and tooling, manufacturers can produce components with details, openings, ribs, bosses, and other features that would be difficult or inefficient to create using some other manufacturing methods.
What Plastic Materials Can Be Used for Injection Molding?
A variety of thermoplastic materials can be processed through injection molding of plastics. Common material families include ABS, polypropylene, polyethylene, polycarbonate, nylon, and various engineering-grade resins.
The appropriate material depends on what the finished component needs to withstand. Strength, flexibility, impact resistance, temperature exposure, chemical exposure, appearance, and other requirements may all influence the decision.
Because no single plastic is ideal for every application, material selection should take place alongside engineering and design considerations.
How Do I Choose the Right Plastic for My Application?
Start with the conditions the finished part will experience. A component exposed to heat may have different material requirements than one that needs to withstand repeated impact or contact with chemicals.
Other considerations can include dimensional requirements, appearance, stiffness, weight, expected service life, and production requirements. The material also needs to be compatible with the planned manufacturing process.
Working with an experienced engineering and manufacturing team early in product development can help narrow the choices and identify potential processing concerns before production begins.
How Long Will an Injection Mold Last?
There is no single lifespan that applies to every mold. Tool life can vary significantly based on the mold’s construction, materials, design, maintenance, production volume, and the plastic being processed.
A mold used occasionally for a lower-volume application may experience very different demands from one used continuously for high-volume production. The type of tooling and expected production requirements should therefore be considered when planning a project.
Discussing anticipated volumes and production conditions with your manufacturer can help establish appropriate tooling expectations.
What Factors Affect Injection Molding Costs?
Several factors contribute to the cost of an injection molding project. Tooling is one important consideration, particularly for a new product requiring a custom mold.
Other factors may include the selected resin, part size and complexity, production volume, cycle time, secondary operations, quality requirements, packaging, and other project-specific needs.
This is why a simple price comparison may not provide a complete picture. A manufacturer needs enough information about the part and its requirements to develop a meaningful estimate.
What Information Do Manufacturers Need to Provide a Quote?
The more complete the project information, the easier it is for a manufacturer to evaluate the requirements. Useful information may include a part drawing or three-dimensional CAD file, material requirements, estimated annual volume, expected production schedule, and any relevant performance specifications.
It is also helpful to identify whether tooling already exists or needs to be developed. If there are specific cosmetic, dimensional, testing, or packaging requirements, those should be communicated during the quoting process.
Providing this information early can help the manufacturer understand the project rather than making assumptions about what the finished part requires.
What Is Injection Molding Cycle Time?
Cycle time is the amount of time required to complete one molding cycle. It generally includes mold closing, material injection, cooling, mold opening, and part ejection.
Cycle time can vary depending on the material, part geometry, wall thickness, mold design, processing conditions, and other factors. Cooling is often an important portion of the cycle because the molded material must reach an appropriate condition before the part can be removed.
Reducing cycle time can improve production efficiency, but it needs to be approached carefully. Changes to processing conditions should not compromise part quality or dimensional requirements.
Can Injection Molding Produce Complex Parts?
Yes, injection plastic molding can produce components with a wide range of geometries and detailed features. However, the complexity that can be produced depends on the part design, material, mold, and manufacturing requirements.
Features such as ribs, bosses, openings, textured surfaces, and other details can often be incorporated into molded components when they are properly considered during design and tooling development.
This is where design for manufacturability becomes particularly valuable. Addressing potential molding issues before tooling is produced can help prevent unnecessary revisions later.
What Quality Control Measures Are Used in Injection Molding?
Quality control can involve multiple stages of a project. Depending on the application and customer requirements, manufacturers may monitor materials, tooling, processing conditions, dimensions, appearance, and finished parts.
Inspection methods should be appropriate for the component and its specifications. Documentation, process monitoring, sampling, and dimensional inspection may all play a role.
The specific quality control program should be established according to the requirements of the project rather than assuming that the same inspection process applies to every molded component.
How Is Automation Used in Plastic Injection Molding?
Automation can support several parts of the production process. Depending on the operation, automated equipment may assist with part handling, material movement, inspection, packaging, or other repetitive tasks.
In some production environments, automation can help create greater consistency and reduce the amount of manual handling required. It can also allow production personnel to focus on activities that require more direct oversight and decision-making.
The appropriate level of automation depends on factors such as production volume, part design, equipment, and overall process requirements.
What Should I Look for in an Injection Molding Company?
Choosing an injection molding company involves more than finding a manufacturer with molding equipment. Consider the company’s engineering capabilities, experience with similar projects, material knowledge, tooling resources, quality processes, and ability to communicate throughout development and production.
It is also worth asking how the company approaches manufacturability. A partner that can identify potential issues during design may provide value well before the first production run.
For companies evaluating plastic injection molding technology, finding a manufacturer that can understand both the technical requirements and the practical goals of the project can make the development process more straightforward.
Find the Right Partner for Your Injection Molding Project
Every molded component has its own requirements. Material, geometry, tooling, production volume, quality expectations, and end use all influence how the project should be approached.
Design Plastics provides engineering and manufacturing services for custom plastic components, including injection molding and vacuum forming. Its team can work with manufacturers to evaluate project requirements and determine an appropriate path toward production.
If you are developing a new component or reviewing your current injection molding strategy, contact Design Plastics to discuss your project and learn more about its manufacturing capabilities.