Mold Making Technologies
Subtract Damage to Add Value
By Daniel Springhorn, president, Diebold Goldring Tooling
Offshore competition. Outsourcing. China. Subsidies. All scary words that
are bandied about quite freely in our industry. Fortunately, they are only
words. Most often, the true obstacle in the path to our success is of our
own making, or at best, our own neglect.
In order to increase our profits
and bolster the success of our enterprise, we can either cut costs or raise
prices. When raising the price is out of the question, how can we cut cost
without negatively impacting our product?
Much has been written about efficiencies of labor, about reducing
machining cycles, and increasing tooling life, but what about simple shop
One of the things that has struck me over the last 10 years of visiting
shops has been the almost universal disregard for the condition of the
toolholder. Harsh, but true. Toolholders are left out on workbenches along
with cutting tools, hand tools, fixture components, and all the other
detritus of manufacturing. The result? Toolholders that are banged, bruised,
nicked and chipped.
Figure 1. An assembly fixture for assembling tooling into
toolholders. Figures courtesy of Diebold Goldring Tooling, U.S.A.
Working with many types of toolholders, this hasn’t presented too much of
a problem. Now, in the first part of what is truly a new millennium in
machining, it is a large and growing problem.
Think about it. When I first started working in the trades, somewhere
around 30 years ago, 5,000 rpm was considered high-speed, a really radical
number. Now I routinely tell customers that we consider “high-speed” to
start around 20,000 rpm. Feedrates and stock removal rates continue to keep
pace with spindle speeds, as cycle times are slashed and accuracy held to
increasingly tight tolerances.
The driving force in this high-speed revolution has not been, as many
suppose, high-speed spindles, but rather, the toolholder/spindle interface,
which allows for higher speeds and better accuracy. You can turn an ANSI
B5.50-94 30 taper toolholder at higher speeds, but the fact is, without
extensive modifications, it’s difficult if not impossible to improve its
accuracy and repeatability.
The HSK interface is the one that seems to be most commonly used to push the
envelope of speed and accuracy. This non-proprietary toolholder is capable
of transmitting large amounts of torque very accurately, but to do so, it
needs to be properly cared for.
The taper diameter tolerance of an HSK toolholder is measured in microns,
and it doesn’t take much of a bump against a tee-nut to make a dent or raise
a burr of more than a few microns. Once that happens, the toolholder no
longer functions as it should.
Machine designers, spindle designers, programmers and process engineers
all use basic knowledge about the performance capabilities of toolholders to
optimize the performance of any given machine tool. When the toolholder is
used for any period of time, it will inevitably degrade. As it does, the
performance of the machine tool will as well.
How to Add Value
This is our chance to add value to our product by subtracting damage to the
toolholders used. Simple things—such as cleaning the tapers and bores of HSK
tooling, proper assembly techniques and proper storage equipment—can go a
long way toward eliminating taper damage and ensuring that your tooling can
deliver all the performance it’s capable of.
- When assembling tooling into toolholders, use an assembly fixture, not
a vise or a spindle (see Figure 1).
- Don’t store toolholders on a bench or in an open factory environment
where they will get covered in oil-mist that attracts damaging particles.
- Train and encourage your machinists and tool crib people to handle and
clean HSK toolholders as the precision parts that they are.
- Use purpose-built carts to transport tooling between crib areas and
the machine itself.
- Restrict access to toolholders and com-ponents to people who actually
need to work with them.
Figure 2. Storage options.
All simple, basic steps (see Figure 2).
Once the storage issues are settled, it’s time to take a look at what you
will be storing. As I noted above, the tolerancing on an HSK toolholder is
very tight indeed. Ask yourself, honestly, if your shop could hold a
tolerance in the range of four microns, or one-and-a-half ten-thousandths of
an inch. This, not just in one point, but along the length of a taper.
Right. Not many other shops can either!
Figure 3. Gauging is available in many different configurations
That said, every time you buy tooling that doesn’t conform to the HSK
standards, it costs you money. Nonconforming tooling may have radically
different performance characteristics than tooling that does conform, and
that could have serious implications for your machine, your spindle and your
It used to be a truism that the end user couldn’t afford to buy gauging
to check toolholders. After all, why should they? 7/24-style holders were
relatively loosely toleranced, and so were the receivers. As long as it
mated, and the parts looked okay, everything was good. Now, it’s close to a
truism that if you are using HSK tooling, you can’t afford to not
have your own gauging. There are many fine, high quality
toolholders on the market today. Conversely, there is a lot of junk out
there as well. It’s impossible to tell by looking at it which is which.
To protect yourself, to protect your investment in machinery and tooling,
and to add value to your products by maximizing the realized benefits of the
HSK system, check your toolholders with certified, traceable gauging to
verify that it is indeed what the salesman says it is.
This gauging, which was once beyond the means of many shops, is now
avail-able in many different configurations, and at a price that makes
sense. Whatever type of gauging you buy, it’s important to remember that
without traceability, the gauge is worthless. You have to be able to see
what the actual gauge master was checked against, who said it measures what,
and when (see Figure 3).
It seems to be a lot of trouble and expense, but looked at against the value
you add to your product by using quality tooling in your production, and by
maintaining that tooling at optimal condition, it really isn’t much. Today,
a difference of a few percent in the bottom line can make or break a shop,
and these small things just might give you that few last percentage points