Product category:
Tool and cutter grinding
News Release from: Schneeberger, J | Subject: Tool and cutter grinding software - complex tools
Edited by the Manufacturingtalk Editorial
Team on 24 May 2007
Software eases grinding of complex
cutters
Software permits the easy grinding of even the most complex tools, with grinding strategy selected according to the cutting out of end cutters.
Cutting tool technology has advanced, allowing machinists far greater options in their production strategies - for instance, most cylindrical carbide end mills now feature a corner radius instead of a sharp corner in order to minimise natural wear and the unnatural stresses which occur in sharp internal corners and are a potential source of fatigue fractures This has put pressure onto the tool manufacturers to deliver ever more complex, precision tools which require more complex grinding strategies in their manufacture
This article was originally published on Manufacturingtalk on 11 Jul 2006 at 8.00am (UK)
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Grinding machine supplier, J Schneeberger, reports that the company had received a substantially high number of serious enquiries at MACH 2006 for its high precision tool grinding machines.
Machine grinds round and flat tooling
Tool and cutter grinder is able to grind round and flat tooling and is equipped with a highly versatile loader, which also accepts both round and flat components.
Aware of the difficulties, Schneeberger has developed software to permit the easy grinding of even the most complex tools.
"One size does not fit all" says Chris Harford, general manger of Leicestershire, UK- based Schneeberger.
"The grinding strategy has to be suited to the particular type of tool to be manufactured in order to create the tool integrity, long life and precision required in high quality tooling.
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Machine grinds micro-tools as small as 0.4mm
A grinding machine has been designed specifically to meet the demands of machining micro-tools as small as 0.4mm and does not exert grinding forces on the work piece.
5-axis machine grinds different broaches
For grinding flat, cylindrical or helical broaches, a 5-axis machine produces exceptionally high accuracies owing to the machine's rigid and robust construction.
The cutting strategy which should be employed varies according to the number of cutting edges, flute depths and flute cutting angles.
If form consistency is important, yet another strategy should be used - depending on the penetration depth of the flute from the cutting edge, for instance, requires defined contact grinding in the radius by means of pitch correction.
In addition, the ratio of radius to slot depth (v=R/Tn) plays an important role." Cutting strategies are defined according to tool specification, for instance corner radius milling cutters whose radius edge is not affected by the run in of the slot shape and are standard tools with a standard helix angle up to 30 deg, slot cutting angle between 0 and 10 deg, slot depth (v) of between 0 and 0.5mm, those with a slot depth (v) of between 0.5mm and 1mm, or corner radius milling cutters with a helix angle of more than 35 deg, slot cutting angle of between - 8 and 16 deg, a slot depth (v) between 0.5 and 1mm.
For this category radius edge correction to ensure specific positioning needs to be carried out.
The grinding strategy within Schneeberger's easy to use proprietary software is selected according to the cutting out of end cutters.
It maybe based on straight cutting out, with the machining space of the end cutter made at the defined orthogonal cutting angle by plunging the wheel straight in, or by cutting out with a movement along the course of the cutting edge and with helix pitch correction to give the radius a guaranteed true shape.
In the case of tools subjected to extreme loads in the end-face region and with small helix angles, the grinding strategy involves straight cutting out with a defined orthogonal cutting edge where the straight machining face covers the entire radius region.
This ensures the entire radius region is corrected by a plane cutting out surface to maximise the lip angle of the cutting edge in the radius region.
Another areas of difficulty is the grinding of multi-pitch helical milling cutters (end mills with various spiral pitches) since four- flute spiral cutters with two different spiral leads have become commonplace because differing pitches result in more stable milling due to the changing direction of normal force from tooth to tooth and minimise the chattering common with higher feed rates.
The Schneeberger proprietary software allows the operator to programme multi-pitch helical cutters as a cylindrical cutter using the 'multi- spiral milling cutter' option in the software.
Primary cut is performed by the pitch of flute one, secondary cut by that of flute 2.
The flutes with the steeper pitch are prevented from running into the back of the following flute by defining the rotary offset.
With unequal pitch it is sufficient to define the offset via the pitch angle.
The software assumes that the two different pitches are distributed in each case over the central and secondary cutting.
The pitches themselves need not be known.
The software ensures similar cutting conditions for all cuts on the periphery.
Multi-spiral milling cutters with corner chamfers and corner radii can be ground using the same software option.
Harford said: "Our task is developing grinding machines which enable our customers to be successful.
That means providing them with capable, robust machines which deliver cost effective, high productivity.
Easy to use software packages are a critical part of that service and one to which as a company we devote considerable R and D resource in order to remain at the forefront of the tool and cutter grinder industry.".
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