Plastic ComponentsWhen developing a new product using injection molding processes, the customer wants to achieve specific levels of product performance. The manufacturer wants to have a certain level of production efficiency. The end user wants to have reliable performance of the product in the field.

All three groups want to accomplish these things within a reasonable budget and time-frame. Design of Experiment is a developmental tool that can find flaws that prevent the achievement of these goals.

Design of Experiment: Math, Performance and Measurements


Design of Experiments is a method that can simultaneously change input variables as well as extract their individual contributions to an output variable. While this is a mathematical tool, the keys to success lie within the non-math activities.

The first step is to determine what needs to be learned.

This tends to be a balance between:

  • performance objectives and sometimes includes business needs (cost, for example).
  • measurements of the results that will indicate progress toward those needs. This also must be determined.


Multiple measurements are not uncommon for a real-life situation when you are using Design of Experiment in the injection molding configuration process. Next, you need to determine the potential input variables that may influence those outputs. This is balanced with the available budget and schedule. Finally, these items are translated into a predefined matrix to allow extraction of the relationships desired.

After the data is collected, a statistical analysis is preformed to provide a mathematical model and to determine exactly what learning has been obtained. Based on these findings either a recommendation for change is made, or further testing is required. This is done in order to make certain deeper learning is obtained. Any step may return to an earlier step if there is a contradiction that needs to be resolved.

Performance Testing for Product and Process Design

Performance testing can include either product or process performance. It can also include an incapable process that could dictate a product change. Using a Design of Experiment approach enables the review of design sensitivities.

This also makes it possible to learn where to tighten certain inputs or relax standards, while still ensuring the customers’ needs are being met. This also creates a more efficient injection molding product. However, other designs require empirical testing as they could not be predicted with current knowledge, so again Design of Experiment is used to understand the aspects of the prototype hardware, and to fill out the design settings. This approach creates a higher level of confidence going into the final and most successful verification testing.

On the process design side, a design and iterative perspective often is lacking. If an injection molding process is not meeting requirements, it may be time to pose certain questions such as:

  • Can this be the right process for the materials?
  • Were the recommended settings being used without proper evaluation?
  • Did you understand what would work for this particular design?


Utilizing Design of Experiment can help you to find the process and parts acceptable to customers and can be utilized for years to continue meeting the customers’ needs.

Product design is a great application for Design of Experiment tools. By developing an early understanding, surprises can be avoided downstream.

Manufacturing Applications: Production Efficiency

Design of Experiment can provide a solution if a poor design was released to manufacturing and the initial homework was not done. It can also be useful if the process outcome was not known and already released for manufacturing.

Design of Experiment testing can create changes in manufacturing that make it so that everyone can feel confident they have discovered exactly the right solution.

Product Reliability and Availability

Design of Experiment can be applied to provide data about a product’s ability to perform in a variety of environmental conditions such as:

  • temperature
  • high humidity
  • high UV
  • aging
  • product wear
  • sensitivity to noise
  • electric voltage

Design of Experiment can also help understand the sensitivities of the design. This approach works particularly well for injection molding product and process design.

It is also true that most difficult situations can be avoided if product and process development in R&D are addressed. It is essential to get the homework done early in order to create a competitive advantage such as getting products to market at a much faster and more confident pace.

Utilizing Design of Experiment when necessary Crescent Industries is a custom injection molder and mold builder manufacturing various plastic components for the medical, pharmaceutical, dental, defense, safety, electronics/electrical and aerospace industries.  To learn more about Crescent Industries custom injection molding services, please click here.

Reference material from: Plastics Business Oct 2012 by Perry Parendo, of Perry’s Solutions, Inc.

Topics: custom injection molding