Optimization of Spin Welding Process for Plastic Part Joining

Overview

Whirley Drinkworks creates anti-condensation cups with two parts, a shell and a liner that are spin welded together to create an airtight seal. The company is experiencing spin welding errors where the parts are not welded correctly or not aligned properly. The group has been tasked with minimizing the spin weld process errors.

Objectives

The group will focus on the spin weld process and minimize errors from the previous processes that impact spin welding itself. This includes part nesting, part location and the spin weld process itself. The group will take an approach that consists of problem isolation and tolerance tightening.

Approach

• Analyze the assembly lines to see if sources of error are obvious to the eye
• Research spin welding process factors
• Decide on a problem isolation procedure to reduce sources of error
• Generate and implement concepts to isolate problems
• Use engineering computations to find the optimal path forward in problem isolation
• Implement and test isolation procedures
• Record large samples of data and analyze against control data to determine the best solution
• Present results and recommendations to the sponsors

Outcomes

The group took a hybrid approach with a design of a new support for one line variant while creating a process optimization guide that applies to both lines to reduce time needed to isolate problems.

• Bottom block support
  • Improved shell location tolerances and removed flexing of walls during welding process
• Process optimization guide
  • Reduced time to isolate problems for technicians
  • Guides technicians in correct practices to find problems