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Toolholders: A Missed Opportunity for Process Optimization?

Posted by: 14. March 2014

 

Between the print and the part lies a puzzle, known as the process. The process includes the machine, workholding, tooling, and program, usually with one or more of these components playing lead dog.  Yes, there’s usually more to the process, but these four elements are always present.  While the print and the part are usually non-negotiable, fixed entities, the infinite possibilities of the process provide the spice of life for part makers. 

Toolholders as an element of the process are too often taken at face value, a missed opportunity for process optimization.  In the case of a turning center, process engineers should know that somewhere within or beyond the standard tool holders and tooling layout schema of every machine, added flexibility and reduced cycle time may be hiding, longing to be discovered. Most basic CNC lathes are equipped with an 8-, 10-, or 12-station turret and an assortment of turning, facing, and drilling/boring holders.  

Even the simplest of lathes, the gang-type chucker, includes tool blocks or holders to handle these three types of tools.   Both of these machine styles use tooling that moves around the rotating part in order to machine it. But as more non-traditional lathes hit the market, more unconventional toolholders emerge.   For instance, Swiss-style lathes, with programmable linear axis spindle travel, can move the part around a fixed tool, so using gang-type tools expands capacity. Twin spindle lathes can utilize the “back” side of a turret for tool mounting.  And additional axes on lathes with secondary milling function may be exploited to enable use of innovative tooling.

The machine concepts that shine the most allow creative tooling strategies to flourish. A few examples: 

Figure A is a tooling layout of the Haas Office Lathe.  It uses gang-type tooling. Notice how close together both square and round tools can be placed on the slide when machining small parts. Turning tools can be placed in the up or down direction, which requires spindle reverse when cutting with one or the other tools, but shortens slide repositioning. Can you imagine mounting a simple milling unit on the t-slotted slide to add even more flexibility?

Figure B features Citizen lathe tooling.  Tool block #1 is a rendering of a gang-type tool block with three tools on the same centerline. Tool block #2 handles two round tools on different centerlines that require Y-axis slide movement. Tool block #3 is similar to #2, but provides power to drive two rotating tools on two different centerlines.  Tools in this holder might drill two holes in the side of the part simultaneously. 

 

 

Figure C is a partial tooling, turret, and spindles layout of a Miyano BNJ series lathe. Notice the two round tools in the same turret position near the top. The dual-tool-on-one-station strategy might be used to drill and ream a hole, which reduces tool-to-tool time.  Notice the tool station just below, with one live tool facing front and the other facing back. This approach takes advantage of space savings while adding flexibility and reducing process time by eliminating a turret index.  Using the same approach with stationary tools is just as effective.

I watched a short Okuma LB3000 EX lathe video which demonstrated their unique 12-station turret “Middle Indexing Function” that can potentially double tooling capacity. It offers another simple, but effective, creative tooling strategy.

These examples all utilize the builders’ tool holders. But if solutions like these aren’t available on your machines, many are so simple that shops can easily implement them on their own.  If making parts is what gets you up in the morning, discovering hidden tooling opportunities will add spice to your life and profit to your bottom line. 

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