First step to precision: back to basics on tool presetting

The precision of metalcutting in CNC machine tools relies on tool dimensions – length, diameter, cutting edge radius and angles, for example – that are exactly defined. Presetters perform this essential task on pre-mounted tools offline, and the benefit of doing so, in terms of productivity, increases with the number of tools processed. German manufacturer Zoller (01283 499566) offers an online tool to help calculate those benefits: http://www.zoller-uk.com/why-preset-your-tools.

Like modern metalcutting machines, what sets apart one tool presetting brand from another is not hardware but software. A streamlined look and feel simplifies the job, particularly for inexperienced users.

Common across Zoller brand presetters is the core interface. An on-screen arrow indicates the direction in which to move the sensor so as to make contact with the cutting edge. Once the device is centred around the tool, a dynamic crosshair image processing system automatically detects the cutting edges (based on an internal database of cutting edge shapes) and performs measurements. Special programs enable the measurement of radial and axial run-out.

Surrounding this core interface are many wrappers: there are three versions of the Zoller software, Pilot 1.0, Pilot 2 mT and Pilot 3.0. As the presetter models increase in sophistication (and cost), more complex operations become possible. As the model numbers increase, touchscreens tend to get bigger and systems sprout keyboards and mice; tolerancing capability improves, as do options for sharing data online.

At the low end, simple software speeds up what is essentially a manual process, while at the high end, the software either takes over completely and runs an automated presetting process, or provides advanced analytical functions suited to an experienced machinist. Particular considerations include: the abilities of those undertaking presetting and their technical literacy; the size and quantity of tools to be inspected; measurement precision requirements; and how tool data is handled in the organisation.

First, as regards user ability, manual presetting systems are relatively simple but may be tricky to customise; automated systems of measurement and data transfer are foolproof but even less flexible. The most capable software requires the most capable operators. Second, each presetter model is limited not only by its measurement envelope but also by its axes – more sophisticated models integrate a fourth axis in addition to Z, X and C (such as the Zoller Hyperion and Redomatic). Also, when large numbers of tools need measuring, automated systems would be faster than manual ones.

As regards precision, pneumatically-actuated mechanical toolholder gripping is almost universal across Zoller machines for example, but optional vacuum systems may prove more precise. (Systems boasting even higher precision tool inspection, for tool manufacturers, are also sold).

Toolsetter data output possibilities across the range run from label printer to list printer to USB stick to serial (RS232) jack for direct numerical control (DNC) linking to machine tools, to computer network integration for linking with connected machines.

The last point is particularly important. Although even entry-level Zoller systems can store a database of cutter shapes (for automatic tool identification), as well as tool adapters and tool measuring steps, data storage options increase in higher-end models. At the top of that pyramid is Zoller’s proprietary Tool Management System (TMS) software, coming in three versions (bronze, silver and gold) for tool management, warehouse management and manufacturing organisation management, respectively.

Wide presetter choice

• Big Kaiser (ITC)
• DMG Mori
• ETG Workholding
• Ezset (Fenn Tool)
• Kelch
• Nikken
• Optima (Bowers Group)
• PCM Tooling
• Speroni (NCMT)
• Tuscan (YMT Technologies)
• Uniset (Mapal)
• Variset (Royal Tool Control)

This article was published in the May 2016 issue of Machinery magazine.