Cutting tool technology Traditional v modern thinking in the die & mould industry
Many shops still cling to technologies they know, especially when it comes to cutting inserts. Doron Cohen, die and mould industry manager at cutting tool manufacturer Iscar, writes that living in the past could affect a company’s future.
The die and mould industry is one of the very ancient industries; one of the first mould-making practices was the production of patterns for coins and medals.
The common mould maker is very qualified and skilled, utilising a wide variety of techniques, including metal removal, metallurgy, polymers, plastic flow, EDM and wire-cut technology.
In many cases, the key persons in some enterprises will say that since mould or die making is not a mass production, there is no pressure to change tooling and technology, since most of the parts are different from one another.
One of the ways to analyse a mould shop’s level of technology is to have a look at its machining methods and tools. It may seem like many of the die and mould producers and standard mould shops have “loyal” feelings to their old tools and instruments.
Die and mould machining can be done with a wide range of cutting tools, which are selected and optimised in accordance with the process chain, process step specifications, final required geometry and surface integrity, workpiece material and its properties, as well as machine tool specifications and different environmental conditions.
Common mould shops still use standard round-shaped milling inserts for their rough milling applications, standard ISO turn inserts for rough turning on a lathe, and a HSS drills or taps.
In the shops, a common saying is that they only have a specific hole to drill and only one or two threads to tap, so why change to newer tools and create higher costs? The savings are so small in regards to time. However, in reality, there is a huge difference for shops that do adopt new technology. Also, adopting new tools with the machine and tool-path technology will definitely make a difference in the long run.
As a result of the ongoing pursuit for higher productivity, faster metal removal and more cost-effective machining processes combined with high performance, Iscar has developed and introduced new cutting technologies, new designs for cutting edge geometry, new cutting tool materials and new coating technologies.
Traditional rough milling
For rough milling of a mould cavity or a core, the pervading idea was that there will be no replacement for the standard round insert geometry; methods of using either an endmill (shank adaptation) or a shell mill (screw and two keyways) with round inserts are well-known and still widely used.
There are many milling applications that are applicable for this type of tooling, such as face milling, shoulder milling, linear and circular ramp milling. This, in addition to relatively low prices for the cutting inserts, is the main reason for the widespread use of round inserts and tools.
However, while looking at each parameter or application of the whole milling process and trying to efficiently optimise the common roughing technology, one realises that new cutting technologies, tools and methods can dramatically change the manufacturing process compared to how things were made in the past.
When milling metal, the round-shaped insert creates different approach angles at each depth of cut. Basically, there is a need to change the machining parameters for each depth. A common method adopted by mould shops is to apply certain consistent machining parameters for all mould parts using the same tool. This may be easy and safe for the shop employees, but it in fact limits productivity and efficient machining.
Iscar has developed a unique and successful milling line, Helido H600, which enables mould shops to expedite the time on the machine for each part. The approach angle is a linear constant 17 or 30 degrees for fast-feed (FF) or medium-feed (MF) implementation.
For each depth of cut applied, the same machining parameters can be used and are well-accepted by the firms which are technology adopters. In addition, they provide very high metal removal rate and machining efficiency.
ISO inserts in rough turning
For several decades, ISO standard turning inserts were the only turning cutters in the market for lathe products. The negative-shaped double-sided insert for medium to rough turning is quite popular.
Rough turning was commonly done with a diamond-shaped (80 degree) insert, while clamped with a well-known lever-clamping mechanism. Under heavy loads, micro-lifts of the back of the insert occur and create micro-chipping and breakage.
One solution was to use a top-clamping mechanism, but only for light depth of cuts since large chips were rubbing the top arm that clamps the insert.
Iscar designed and developed an innovative diamond and trigon-shaped turning line of tools and inserts, which is called Dove IQ Turn, where at the clamping face there are dovetailed prisms, which prevent movement even under extremely high loads. This provides increased tool life.
Technology adopters will surely use the inserts and toolholders, but will common mould shops follow suit?
The world of metalworking is being constantly updated by new machines, tool path software and cutting tools. Adopting the latest technologies and having an open mind to test them will bring innovative solutions and ideas to the common, relatively old-fashioned mould shop.
It will be of benefit to them to come to the conclusion that the development of new cutting tools, combined with the various machining processes and the complete process chain, is essential for higher productivity and improved performance in the manufacturing of dies and moulds.