Case Study

Process Consolidation and Custom Collet Design for Cycle Time Reduction

Project Overview

Arlett Solutions was engaged to improve the machining efficiency of 4.00 mm diameter screws (30–60 mm length), covering a total of 35 SKUs. The objective was to consolidate operations, reduce cycle time, and improve part stability and surface quality without compromising precision.

Initial Process State

The screws were machined on a STAR SV20 lathe using a two-operation process.

·       Operation 1 – Main Spindle

·       Mill flutes

·       Cut threads

·       Deburr

·       Cut-off

·       Transfer to sub-spindle

·       Operation 2 – Sub-Spindle

·       Mill face

·       Drill chamfer

·       Broach hex

·       Deburr

·       Eject part

This configuration resulted in a 5-minute cycle time per part, surface marking risk during broaching, and limited part stability during secondary machining. The traditional collet design allowed the screw head to rest on the edge of the collet, creating the risk of gouging during broaching and potential axial movement during drilling operations.

Engineering Solution

Process Optimization

·       Revised Operation Structure

·       Main Spindle:

·       Mill flutes, cut threads, deburr, cut-off

·       Sub-Spindle:

·       Secure part in newly designed custom collet

·       Mill face

·       Spot drill for broach and drilling

·       Drill

·       Broach hex

·       Deburr hex and chamfer

·       Eject part

Custom Collet Development

A redesigned collet was developed to improve clamping stability and eliminate head damage.

·       Limitations of Existing Collet

·       Head supported on sharp edge

·       Risk of gouging during broach operation

·       Increased potential for axial movement

·       Modified Collet Design

·       Integrated precision-machined radius pocket

·       Allowed screw head to seat slightly within the collet

·       Improved axial support during broaching

·       Eliminated edge contact responsible for surface marking

·       Reduced risk of part movement during drilling and broaching

Results

·       Cycle time reduced by 50% (from 5 minutes to 2.5 minutes per part)

·       Labor savings of 2.5 minutes per part

·       Improved surface finish consistency

·       Reduced quality risk

·       Increased overall process stability

Conclusion

Through process consolidation and precision workholding redesign, Arlett Solutions achieved significant efficiency improvements while enhancing part quality and operational stability. The project demonstrates a structured engineering approach focused on measurable results and sustainable process optimization.