A missing screw defect could make for a product recall.

1. Solidworks Simulation
A prediction of an
optical assembly
alignment error
03/22/2016
Don Blanchet
3B Associates

2. Problem
 Optical sensor assemblies have been shipped to
customers with defects. Screws without loctite
thread lock.
 Loose screws were found in the shipping container
of some top assemblies.
 All units have been deployed.
 There have been no reported optical errors.
 Estimate the potential axis alignment error to
establish a recall schedule.

3. Precision machined Assembly
lens

4. Precision machined Assembly
lens
Alignment
Axis
Center line of
lens

5. FEA mesh - 450,000 d.o.f.
Maximum
10g
Acceleration load

6. Result –max gap at missing
screw location = .0025 inches
lens
Alignment
Axis
Center line of
lens

7. Result optical axis
deviation - .0044 inches

8. Conclusion
 The single missing screw will add to
the optical misalignment budget.
 At the peak of the worst case load of
10G an additional alignment error of
.0044 inches is predicted.

9. Conclusions