top of page
vhbfixture9.png

Adhesive application fixtures

Spring 2019 - flex
Purpose

To independently design & build two fixtures for the assembly build of 150+ kitchen appliance units for a client. One fixture aligns die-cut VHB adhesive to the flex circuit (Fixture 1) and another fixture compresses and bonds the VHB to the plastic ring (Fixture 2)

design elements

  • HP MultiJet Fusion printed Nylon PA12 parts (Fixture 1)

  • Laser Cut Acrylic parts (Fixture 2)

  • Spring loaded button translating vertical motion to radial pressure (Fixture 2)

  • Magnetized return feature of radial pressure parts (Fixture 2)

  • Toggle clamp to allow mostly hands-free operation (Fixture 2)

  • Made use of in-house excess hardware & stock plastic sheet for assembly

  • Reduced time & difficulty to do both processes by hand

design narrative

This kitchen appliance assembly has a flex circuit adhered by VHB adhesive in four areas to a plastic ring, with tiny components on the backside of the flex circuit that cannot be crushed or broken off. Each rectangular area where VHB is placed is smaller than a human fingertip, which made manual assembly awkward and error-prone. The VHB then needed to be bonded to the plastic ring by applying a ~60% compression for around 15 seconds. I was tasked with creating fixtures to aid in both processes.

​

The first fixture I made was assembled with parts that I laser-cut in the lab, sized to fit hardware that we had. It fixed the flex circuit flat and in place using placement pins that fit into the existing holes in the flex. Once fixed in place, the assembler could use tweezers to position each VHB in its place. The holes in the bottom plate allowed the components to fit through so they weren't crushed.

Exploded View of Layers
flexfixtureexpl.png
flexfixture3.png
IMG_20190329_151142.jpg
CAD Assembly
Final Fixture - I ended up switching the orientation for better ease of use

The second fixture was for the next step in this process, whetting the VHB with around a 60% compression for 15 seconds to a plastic ring that was a part in the overall assembly.

​

I started with a spring-loaded button idea that translated the vertical movement into 4 radially pushing wedges, with the plastic ring resting right outside the wedges, and found a clamp handle that would have the vertical travel necessary. When the wedges pushed outwards, they would compress the VHB on the flex circuit against the ring. When the button pressure was released, the wedges would retract due to the magnets on the inner slanted surface of the wedge. This design and mechanism is shown below:

vhbfixture1.png
vhbfixture3 (1).png
Initial Concept - Fixture 2
Cross Section Initial Concept - Fixture 2
Button Press Wedge Mechanism

After a design review with my team, we determined that the handle would get in the way of actually slotting the plastic ring down over the top of the fixture and provide a risk for damaging components. After this realization, I switched the design over to use a toggle clamp instead. The final design is shown below:

vhbfixture9.png
Exploded View Final Concept
vhbfixture10.png
CAD Final Concept
IMG_20190326_155417.jpg
Final Concept Build
conclusions & acknowledgements

These fixtures were a great way for me to think about motion translation and process improvement in an assembly line flow.

​

Thanks to Peter for his mentorship & suggestions, and the rest of the ME team for their guidance and design feedback.

bottom of page