pre-design verification fixturing: force testing

Problem

The company’s products required fixtures to stabilize and a method of actuation for each component during force measurement tests.


Objective

To design and develop fixtures and test protocols that can securely hold and smoothly actuate each component to accurately gather force measurement data.

Skills Employed

  • SOLIDWORKS 3D CAD model and 2D drawings with tolerances
  • 3D Printing FDM
  • Laser Cutting
  • Working with 80-20 rails, linear bearings, structural brackets, fasteners
  • Snap-fits and cavity designs
  • Machine shop manufacturing and tool use (chop saw, tapping, drills, sanding)
  • Working with heat set and press fit inserts, ACME lead screws, thumbs screws, set screws
  • Chatillon Force Measurement
  • Testing fixture design/mechanical testing
Image of Fixture C Real FDM
Figure 1. Fabricated Fixture for Pre-Design Verification Compression Force Testing
Image of Fixture B Real FDM
Figure 2. Fabricated Fixture for Pre-Design Verification Compression Force Testing for another device component

Approach

After being tasked with designing and prototyping fixtures that would help stabilize and actuate components during force measurement tests, I started to sketch some ideas of how this fixture would operate and function. Then I started designing the fixtures in SOLIDWORKS. After finalizing the designs, I ordered the necessary parts from McMaster-Carr including the 80-20 rails, brackets, and fasteners.

A shell-like clamp was adapted for all fixtures to securely hold the products in place. Each fixture’s base is made of 80-20 to allow for secure placement on the Chatillon Force Measurement Base Plate. A linear bearing was added to Fixture A to help adjust the component into place before and after testing. All fixtures also had a mating component which would help with actuation. I then printed the fixtures with ABS plastic on the FDM printer. Following a few test prints, adjustments were made on the designs of the fixtures. After a few trial test runs, test protocols were drafted and I helped train a co-worker on one of the force measurement tests.


Image of Fixture A
Figure 3. 3D CAD Model of Fixture A - Compressive Force Testing for Device Component A
Image of Fixture B
Figure 4. 3D CAD Model of Fixture B - Compressive Force Testing for Device Component B
Image of Fixture C another angle
Figure 5. 3D CAD Model of Fixture C - Compressive Force Testing for Device Component C
Image of Fixture D
Figure 7. 3D CAD Model of Fixture D - Force Testing for Device Component D

Results

The fixtures successfully stabilized each product and allowed for consistent and accurate measurements. Additionally, the test protocols were drafted and used to help others gather measurements.

Image of Fixture C Real FDM
Figure 1. Fabricated Fixture for Pre-Design Verification Compression Force Testing
Image of Fixture B Real FDM
Figure 2. Fabricated Fixture for Pre-Design Verification Compression Force Testing for another device component

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