Finding the Right Surface Finish

Molded parts are everywhere — from highly cosmetic housings hiding in plain sight to internal components where a fine polish is unnecessary. Most people pay no attention to the surface finish on those parts, but for product designers and engineers, it’s an important design consideration.

Identifying the right surface finish is dependent on a few important elements, namely the development or production stage that your parts are in, the materials they’re being manufactured in and their end-use applications.

On custom finishes, use color coding to provide a clearly marked image of your CAD model with its required finishes.

This month’s tip discusses:

  • available surface finishes for injection molded parts at Proto Labs
  • how to create a custom surface finish involving two or more finishes
  • navigating finishes within ProtoQuote
  • why gating and ejection play a limited role in liquid silicone rubber parts
  • secondary options applied to magnesium components

Read the full design tip here.

3D Printing Fully Functional Parts with Selective Laser Sintering

Selective laser sintering (SLS) is an industrial-grade 3D printing process. It builds durable nylon prototypes and functional parts using a laser that “draws” slices of a CAD model in a bed of material, fusing micron-sized particles one layer at a time. The result is fully functional plastic parts that might have been otherwise challenging to manufacture using machining or injection molding.
This month’s tip discusses:

  • Properties and applications of various nylon materials
  • Managing the SLS build process
  • Design elements to improve eventual moldability
  • Surface finishes and post-processing
  • Maximum part size, achievable tolerances and other considerations.

Read the full design tip here.

Why Stereolithography is Built for Prototyping

Stereolithography (SL) is an established additive manufacturing process that can quickly and accurately create complex prototypes. Parts are built by curing paper-thin layers of liquid thermoset resin with an ultraviolet (UV) laser that draws on the surface of a resin to turn it from a liquid to solid layer. As each layer is completed, fresh, uncured resin is swept over the preceding layer and the process repeated until the part is finished.

SL offers a range of plastic-like materials to choose from with several types of polypropylene, ABS and glass-filled polycarbonate available. Normal, high and micro resolutions are achievable at Proto Labs, meaning very fine details and cosmetic surfaces are possible. As a result, minimal “stair stepping” is seen compared to printed parts such as fused deposition modeling (FDM).

SL parts can also be built to a max size of 29 in. by 25 in. by 21 in., giving it the edge over other additive processes like selective laser sintering (SLS).

Our latest design tip looks at these and other manufacturing considerations for the stereolithography process.

5 Design Considerations for Multi-Cavity Molds

Moving from a single cavity mold to one that produces two, four or eight parts at once seems like an easy way to increase production volume and reduce part costs. This can be true in many cases, but only if the right steps are taken and the requisite homework done first.

The 3D CAD model for a multi-cavity mold.

Designing a part for multi-cavity molding is not as simple as copying the CAD file for a single-cavity mold multiple times. It’s important to recognize that parts that behave perfectly in single-cavity mold might not play well with others, at least not without first making some tweaks to the part, the process or even the material.

In July’s tip, we look at important design considerations for multi-cavity molds that include gating, side-actions and pick-outs, material flow and how family molds are used differently than multi-cavity tooling.

Read the full design tip here.

Design Tip: Leveraging Low-Volume Injection Molding

Investing $50,000 or more in high-volume steel tooling is an inherent financial risk that comes with a move to large-scale production. Compounding the risk is months of idle time as you wait on your steel tool to be ready when you could be iterating part design or even producing products that generate revenue.