We recently introduced the term Design for Manufacturing or Manufacturability (DFM) on our blog, but often knowing what is involved doesn’t 100% translate to what a concept can offer for benefits. While DFM can offer opportunities to prevent problems, it can greatly improve quality as a whole. If you’re wondering how, read on as we further dive into DFM and its benefits.
How Can Design for Manufacturing Improve Injection Molding Quality?
Defining what quality means is a little bit of a challenge. In manufacturing, “quality” generally means that the product has distinguished characteristics that satisfy defined needs with a degree or grade of excellence. That can both be through the manufacturing process and in the hands of the customer. Design for Manufacturing should be done at the beginning of the lifecycle with the intent of designing a product to be simple to manufacture. This phase also allows for the identification of materials to be used, tooling and secondary processes required, and the dimensional tolerances needed to meet the customer’s demand. So how does DFM improve quality to ensure a happy customer?
Some of the items that DFM should cover include:
- Creating a DFMEA Process Sheet – A DFMEA process sheet does many things for your manufacturing operation. The first benefit is to list out every step in the manufacturing operation. The process of writing it down can reveal forgotten or discounted steps. At each step of the manufacturing process, you should look for ways to reduce the required number of items needed to complete the step. The second benefit of a DFMEA process sheet is to brainstorm every conceivable way that a mistake can be made in manufacturing. By focusing on error prevention, the manufacturing process will produce less defective products that need extra work to meet customer criteria or to be discarded. Your manufacturing operation will have an improved through-put ratio, more happy customers, and quality that is at an elite level.
- Identifying Strategic Datum Features – One way to improve product quality is to take the guesswork out of manufacturing. A datum scheme conveys which feature of an assembly to connect first, second, third, and beyond. When properly used in manufacturing, a datum scheme will cause a misalignment when completed out of sequence and the final manufactured product won’t operate as intended. The datum scheme will indicate when poor quality is present and signal a repair is needed before it leaves the facility to a customer.
Datum structures and attachment features will need to be designed into the injection mold. The designers need to balance strength of the features for assembly, and prevention of visual defects like sink marks and knit lines.
- Adoption of Standard Fasteners and Torque – You may find that your product needs to utilize fasteners for attachment purposes between components or assemblies. One common error that can make it to the customer is the incorrect use of common fasteners. An assembly may use multiple types of fasteners for varying strength and durability, but if any fastener can be used at any other point than its intended placement you can imagine it will be done in error. The best-case scenario is to use the same fastener at every point if that is possible to remove the decision of which goes where. If that can’t be done, your DFM study should indicate that the fasteners need to be at separate workstations to prevent confusion that will potentially affect product quality. Complex designs may require multiple torque requirements, and these differences can cause chaos in manufacturing also. When multiple fasteners and/or torque requirements are needed, you may need to adopt fasteners with differing sizes or head shape to prevent confusion of which torque is to be used on what fastener. The easiest way to ensure low product quality can be made is to make every tool fit every fastener at a workstation.
The injection mold will need to incorporate bosses for fastener attachment. That may utilize the fastener directly into plastic bosses or threaded metal inserts that can be inserted or heat staked in place. DFM should take into account how to use the correct inserts, and prevent the wrong torque and fasteners being used. DFM should incorporate mold design features that prevent errors from being produced and low quality being sent to the customer.
- Implement JIT Options with Kitting – Just-In-Time (JIT) sub-assemblies and kitting from different workstations may add efficiency to the overall manufacturing line. DFM should be able to incorporate flexible ideas that make production variable for manpower changes, product volume changes, and the addition of automation. The manufacturing line may involve multiple pieces that require a lot of floor space and walking to collect each part. Designing a small cart may allow for only the correct parts to be delivered to the assembly area as the time they are needed.
Injection molding can assist with JIT and kitting by incorporating ways to identify which part is correct and simple ways to assemble the parts. If the assembly has multiple color options, perhaps a replaceable feature can indicate what color the part should be to prevent red parts assembled to blue assemblies. Injection molds can also incorporate design features that prevent the wrong parts assembled together.
Final Thoughts
Designing for Manufacturing (DFM) means you have thought about how to manufacture a product with minimal errors and improve your product quality to ensure customer satisfaction. Some Computer Aided Design (CAD) software includes various built-in tools that can aid designers in prediction, and some of the know-how will come from experience. SEA-LECT Plastics has an elite staff of designers and manufacturing professionals that design and produce world-class products. We have the knowledge to make your design simple, cost-effective, at an elite level of quality, and the turn-key assembly options to produce it in-house in Everett, Washington. If you have a new idea, call us (425) 339-0288 or email us at mattp@sealectplastics.mystagingwebsite.com. We can offer you advice on the best technology to use, the best materials to meet your product demands, and how to navigate through each development stage with ease.
Matthias Poischbeg was born and raised in Hamburg, Germany. Matt moved to Everett, Wash., after finishing his bachelor’s degree in business in 1995 to work for Sea-Dog Corporation, a manufacturer, and distributor of marine and rigging hardware established in 1923.
In 1999, Matt took over the reins at Sea-Lect Plastics Corporation, a sister company of Sea-Dog and a manufacturer of plastic injection molded products with an in-house tool & die shop. Matthias Poischbeg is also a contributor to Grit Daily.