Accessories in action: Tool Presetting

Courtesy of All Images: BIG Kaiser Precision Tooling

An mptec indicator stand, type SU/F.

Using accessories to maximize machine performance.

Machine tool accessories can offer economical solutions to many tooling and machine setup issues. Used in combination with a machine that delivers the speed and features a shop needs, accessories can help improve productivity and reduce machine failures. This article examines the benefits of several key accessories, including spindle maintenance tools, toolholder maintenance tools, covers, indicator stands, chip fans, tool assembly devices and specialty workholding devices.

Managing the Spindle

The spindle directly affects any machine’s performance, so it should be regularly cleaned and checked. A spindle maintenance checklist should start with inspection of:

n retention knob pull force,

n amount of dynamic runout,

n accuracy of mating surface, and

n cleanliness of mating surface.

Use a retention-knob pull-force gage to test the drawbar force on a regular basis. Service is required if the drawbar force falls below the minimum level stated by the machine builder. Continual operation with low drawbar force can lead to poor surface finish and tool life and increase the chance of damaging the toolholder and spindle.

Dyna Force retention-knob pull-force gage.

Managing spindle accuracy is critical to achieving superior part quality and extending spindle and tool life. To ensure spindle performance, runout must be controlled. Regular inspection with a precision gage bar can help identify potential problems and reduce downtime, spindle repairs and tool and toolholder damage.

A gage bar tests runout and spindle accuracy (see photo on page 70-S). It is a perfectly concentric steel cylinder that measures spindle rotation against its centerline. Lower runout increases output and extends tool and spindle life. Use visual inspection and gages to check spindle geometry. The internal geometry that establishes the spindle centerline needs to be free of defects and contamination. For dual-contact toolholding solutions, the spindles face must also be clean and properly maintained. As the spindle is an interchangeable interface for all toolholders, a damaged toolholder can transfer defects to the spindle and a damaged spindle can corrupt toolholders. Excessive spindle wear can only be corrected by regrinding or replacement.

The optimal operating environment for a machine spindle is free of dirt, oils and other contaminants. Cleanliness directly affects accuracy, and dirt can degrade rigidity of the machine tool/toolholder assembly. Particles and other contaminants cannot be allowed to gather between the two mating surfaces.

Spindle cleaners help maintain spindle precision and prolong machine tool, cutting tool and toolholder life. Use spindle cleaners several times a day to wipe spindle contact surfaces. Implementation of a rigorous spindle-cleaning schedule will have virtually no negative impact on machine tool output.

Managing Toolholders

The relationship of the tool to the toolholder is just as important as the relationship of the toolholder to the spindle. Unlike spindles, which can operate within the controlled environment of a machine, toolholders are exposed to many pollutants. During storage and between uses, toolholders can be contaminated by oils, dust and other particles. The toolholder’s exterior should be cleaned before it is placed in a toolchanger or spindle.

Dyna Test precision gage bar.

External toolholder taper cleaners are available for most common spindle types. HSK, CAT and BT toolholders can have their contact surfaces quickly wiped clean.

Prior to tool insertion, internal toolholder cleaners should be used to remove contaminants from surfaces that contact the cutting tool. Multiple cleaners are available for various toolholder styles, including shrink fit, side lock and milling chucks.

All toolholders have a better chance of delivering the tool to the proper location and holding it firmly when components are clean. Complex toolholders such as collet chucks should be completely disassembled and cleaned between uses.

Wipers are available to clean the internal surfaces of the collet body (see photo on page 72-S). The spring collet should have contamination removed with ultrasonic or high-pressure washers. Nuts should also be cleaned to assure uniform load pressures on the spring collet.

Inside the Enclosure

T-slot covers are protection plates that prevent chips and coolant from collecting inside a machining center’s T-slots. When slots are not being used, these covers can be easily moved into place to keep T-slots clear of debris. These aluminum inserts are simple to remove and deliver a clean machining surface to work from when changing setups. They also keep chips on top of the table where they can be easily brushed or washed into the chip conveyor system.

Covers keep chips out of machining center T-slots.

Certain industries, such as aerospace and medical, require near perfection in machining. Articulated stands can help deliver that for multiple applications by combining high clamping force with a high-precision adjustment rocker to allow operators to fine-tune dial gage settings (see photo on page 68-S). These stands typically have two or more pivot points to deliver positioning precision and an indicator tip for exact measurements in the micron range.