Traditionally, in the metalworking industry, machinists were prized for their ability to achieve precision results through their creative fixture construction and their ability to maximize output. One of the shortcomings of this approach was the very individualized results achieved this way. This methodology had numerous limitations including the need to build the fixturing each time the job was run, resulting in variations in output and quality. Setup time was a serious limitation in overall productivity, as well. With the growth in the popularity of CNC machines, much of the variability was removed; however, setup was still a serious concern.
In recent years, a new approach to fixture construction and change out has been developed. Quick-Change fixturing takes advantage of the features of the machine tools, such as extreme accuracy and high speeds/-high forces, and the increased emphasis on maximizing spindle utilization to dramatically improve productivity Quick-Change Systems allows fixture change out to be completed in minutes rather than hours, since the location of the fixture within the machine is known. This setup reduction becomes very powerful in maximizing machine utilization as well as facilitating smaller run quantities to aid in creating a lean environment.
To provide for this certainty of location Quick-Change systems have two roles; locating and retention. The system must provide accurate location of the tool and then it must have some provision for the retention of that tool once in that location. Different systems types have different approaches to resolving these issues and each has specific strengths and weaknesses.
Quick-Change System Types
Quick-Change systems primarily consist of two types: Mechanical and Power. Mechanical systems use hand operated tools, like an Allen wrench, to engage and disengage the system while Power types use some power supply like hydraulics for actuation.
In Quick-Change Workholding, Time is Money
Typically, systems that have the “slowest” quick change time and accuracy have the lowest cost of acquisition and implementation. Systems that can be fully automated typically carry the highest acquisition costs. Determining the appropriate system for your application will depend greatly on the number for fixture changes in a given period. The more changes the greater need for speed and accuracy.
Best Practices for Quick Change Workholding
Design for Interoperability
Not only amongst like operations (i.e. – all VMC fixtures are interchangeable) but also for downstream operations. This reduces the need for additional clamping/positioning operations, improves flexibility creating improved Manufacturing Planning.
Understand your ROI
Do not discount the interruption to production during any transition period. It is also easy to forget to include fixture modification cost in your ROI.
Use our calculator to help determine your ROI