MOULD TOOLS & MOULDING LOW VOLUME DEMAND PROMPTS INNOVATION
Only when we know the design is correct do
we make the tool. It’s saved us a fortune.”
The initial experience was with Stratasys
FDM (fused deposition modelling) machines
and that is the technology employed today
by Plastic Parts Direct, which now has three
Stratasys machines for prototyping, although
one is really a trial machine.
He continues: “That was the initial drive
for us to go into 3D-printing, for our own
purposes, not for anybody else. But then our
customers would say they had various parts
that they wanted to print rst and found that
we had 3D-printers. So, we printed parts for
them and then we started making jigs and
xtures for them, too, in support of
machining operations, for example. Simple
operations like drilling, but the aluminium
jigs that they were getting made were
costing several hundreds of pounds. 3D-
printed versions were around £120. That
would have been around 2014.”
Now, this 3D-printing of sample parts for
customers didn’t translate into follow-on
mould tool and moulding business for
Plastic Parts Direct (www.plasticpartsdirect.
co.uk). Much would go on to be made in
China. But the company has built its mould
tool and moulding business up another way,
competing on cost and delivery for tools,
and latterly as even that proved unable in
some cases to provide a cost-effective
solution has honed its 3D-printing expertise
to deliver a new service, injection-moulded
parts produced using 3D-printed tooling.
Bowes explains that in the company’s
build-up years, it was making one or two
steel moulds a month, but over the past few
years Plastic Parts Direct has increasingly
promoted modular tooling (pre-made,
standardised bolsters and pre-cut cavity
blanks), mostly in aluminium backed by high
speed machining of cavity details. That high
speed machining has been delivered via a
Hurco machining centre (www.is.gd/ahujuy)
and a Nakanishi 50,000 rpm electric spindle
attachment (TS Technology, www.is.gd/
adegig) that allows cutters down to 0.8 mm
diameter to be employed. Zero-point
workholding has also boosted productivity in
the manufacture of modular tooling. Today,
up to eight mould tools a month are now
being made, with that increasing month on
month, reports the managing director.
This increasing volume of modular tools
over recent years has been driven by a
growth in the number of jobs requiring
shorter runs. Standardised modular tooling
can be available in two weeks versus four to
eight weeks, is less costly overall, with the
further bene t of aluminium modular tooling
being a £2,000 advantage over steel,
important if only 1,000 parts are required.
So, customers have moved to that lower
cost solution. There have to be some
concessions made on, say, sharp corners –
that 0.8 mm cutter, so 0.4 mm radius, is as
good as can be machined, otherwise its
EDM, which is extra cost and time.
MOULD TOOL LIFE QUESTION
On production run length, Bowes cites an
eight-year old eight-impression aluminium
mould tool that is still making 240,000
units/month. This longevity issue is the one
that customers require some convincing on,
he says. Moving parts in aluminium mould
tools will see them wear faster, he admits,
while surface nish can be much better from
steel moulds. However, since many of the
parts moulded are not visible when in use,
nish is incidental.
Over the past three or four years, new
product projects have become a growing
proportion of the enquiries being elded
today by the company, with as many as
three-quarters looking for very short runs,
many of them for product trial purposes.
Small annual volumes of existing assembled
products are also a driver, with companies
looking to substitute more expensive part
machining for moulding, again meaning low
quantities. “So, they don’t need many parts,
but they do need mouldings, not 3D-printed
parts,” Bowes emphasises, adding that
quantities in some cases can be just a few
10s of parts, maybe up to 500. Costeffective
as it may be, modular aluminium
mould tooling, even at the base price of
£3,000, is going to struggle to offer a
competitive answer versus machining, so
almost all enquiries of that nature died, he
reports, adding: “There’s nothing to ll that
gap between moulded parts and machined
parts. But it occurred to us that we could
3D-print the tooling; surely that’s got to
work, we thought.”
So started a journey of 12-18 months’
development work to establish the process
to get to a point where results were good for
a certain selection of parts. Says Bowes:
Building a 3D-printed mould tool.
The secret is in how to keep the insert external surfaces fl at
www.machinery.co.uk | MachineryMagazine | @MachineryTweets | July/August 2020 19
/(www.plasticpartsdirect
/co.uk
/ahujuy)
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/www.machinery.co.uk