Injection Molding Design Tips for Plastic Medical Part (2)

These 5 tips are the sequel to the previous article ( Injection Molding Design Tips for Plastic Medical Component(1) ), in order to help you to understand the limitations and challenges faced of the plastic medical injection mold products.

5. Add Draft

Draft is according to the angling of otherwise vertical walls to prevent constant contact with the molding cavity during the plastic medical mould opening. All vertical walls oriented normal to the direction of mold pull will draft ideally at 1 degree minimum. There is a special consideration for both ribs and bosses, textured surfaces will need to add 1 degree per side for each .001" depth of texture. Draft is an indispensable element in the component design process.

6. Gating and Ejection

Gate location is the area where the material will be entering and filling the cavity of the part. It is important for you to keep in mind the location you intend to gate your component and possibly make provision. There are some questions: Is this gate at the location where the material will flow from a thick walled to a thin walled region of the part? Am I allowed to have a gate mark where I am envisioning my gate? and you must also consider ejector pin marks that will most likely show up on the underside of your plastic medical injection mould parts. If ejector marks are not allowed, you must be called out on your print so other ejection alternatives can be considered.

7. Watch the Sharp Corners

Avoiding Sharp corners as much as possible. These will result in weak points and then lead to part failure and cracking. Adding radii to sharp corners can reduce the molded-in stress. Radii redistributes the stress more evenly and facilitates the flow of the material and ejection from the plastic medical mold. Stresses rapidly amplify when inside corner id less than 25% of the nominal wall thickness of the component.

8. Structural Support

If you are a medical part designer you must want to minimize the amount of material required in filling your part and increase its structural integrity in the same time. Thin walls need some support to ensure the walls won't warp or collapse. Ribs are commonly employed on injection molded components to stiffen relatively thin parts. Ribs, bosses and other projections on the piece part wall will strengthen your part, but it can contribute to other molding issues if you done incorrectly.

9. Secondary Operation or Molded In?

Sometimes you have inserts that need to be fixed inside your medical mould part. You need to consider whether they get molded in or they are pressed or welded in after the medical molding has commenced. Both options are viable and have economic benefits. Do you want a higher priced tool that can accommodate inserts to be molded over, or do you press them into the medical part after the fact? For low production runs, considering a post molding operation is worth to do. For long production runs, it might be more beneficial to mold the inserts. It all depends on the customer's viability, the preference, and the project's budget.

10. Material Selection

The material selection process can be simple, also can be complex. The first step is to define your plastic injection medical component requirements. It's important to narrow the choices process of elimination. What specific property requirements are there? Do you need it to be rigid, flexible, elastomeric? Is there a specific application? Medical? Sometimes the best thing to do is to not reinvent the wheel and do a search history for similar commercial application s if possible, then call up the material supplier for recommendations.

You can contact us for more information about the plastic injection medical mould and other plastic mould. As a professional China a plastic mould manufacturer, we will try our best to solve all your problems for you, contact us immediately for more plastic mould information.