In the manufacturing industry, a commonly used acronym is DFM. It stands for design for manufacturing and it refers to the various factors going into a design so that it can be manufactured at the lowest cost possible without sacrificing quality.
When a product is designed for manufacturing the goals are: reduce cost by focusing on standards, shorten the development cycle, and to reduce unnecessary costs related to labor, overhead, and material.
If you are involved in the development of projects involving plastic injection molding there are a few things you will want to know in order to achieve the best part possible. Let’s dive into five critical tips you can use to optimize your project.
Know the Direction That Your Tool Will be Pulling
Plastic parts are all made in molds. Molds are made of two halves, the core, and the cavity. If possible, all of the features in your part should be situated in the direction that the mold will pull apart in a way that allows them to freely clear your mold’s steel conditions.
If you have features on your part that are situated in a direction other than that of its mold’s pull it can still be molded. Your tooling will be more complicated because it will need added slides and other features which will increase cost.
Is There an Undercut in Your Design?
One thing you need to be aware of when it comes to the design of your part is whether or not there are any undercuts. Undercuts can very easily become stuck in the tool, which is likely to cause damage to your part during ejection.
Have You Added Draft?
Not adding draft in your design is one of the most common mistakes made during part design. If you know for sure that your prototype design is going to be injection molded you need to make sure that you add draft at the very beginning of the design process. If you do this your design will be easily transferable to injection molding. Because of this, the transition to production will be much smoother than if you were to neglect the draft angle and try to add it at a later time.
Have You Factored in Surface Finish?
How the draft angle will affect your surface finish is another vital piece of knowledge you need to have. Without a proper mold draft angle, your part will drag on the surface of the mold when it opens causing your part to suffer unsightly scratches. Scratches on the surface might render it completely useless depending upon what your standards are for cosmetics. This is a massive problem which can be avoided early on in part design. Especially for cosmetically critical parts.
The reason that parts require draft is that thermoplastics shrink when they are cooling in the mold. This creates a large amount of tension on the surface of the part, which is what causes it to stick if no draft angle has been included.
Strive For Consistency in Wall Thicknesses
When you have a thick area in a part it has typically been designed that way in order to improve the strength of the part. But thick parts increase cooling time and uneven thickness can create areas of sink. Many designers make their parts thick in an attempt to provide as much strength as possible, but this can end up making parts weaker in the end when it comes to plastics.
Instead of adding thickness for strength find out from what direction the part will experience the maximum force. This will tell you what areas need to be reinforced. Then you can use ribs, gussets, and bosses to improve strength rather than increasing the thickness.
DFM remains one of the most crucial steps in the process of part design and injection molding. Depending on how thoroughly you consider all the aspects of your part and how they lend themselves to manufacturability, design for manufacturing could end up making or breaking your project launch.
If you want to partner with a company that knows this process well you should consider New Berlin Plastics. We offer DFM services that will include an in-depth review to reduce cycle time and ensure that you have an efficient mold design.
Want to know more? Reach out to us at 262.784.3120 for recommendations on how you can reduce costs and improve your end-user experience!
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