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158
S
eptember
2011
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A
rticle
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WL = Wiper die length
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CD = Collet depth
•
SLx = Straight length (where x is the last straight)
•
CF = Clearance factor (5mm)
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ALy = Length along the arc (where y is the last bend)
•
LL = Limiter length (Distance from tangent at which the collet
housing will encounter interference)
Arc Length Formula:
AL y = (Π * CLR / 180 * DEGREE OF LAST BEND)
Limiter Length Formula:
LL = WL (Pressure die length is not considered)
Collet Stock Formula:
LL + CF + CD – SL x – AL y
Using the sample data:
•
LL = 100mm
•
CD = 30.15mm
•
SLx = 48.45mm
•
ALy = (Π * CLR / 180 * 50.79) = 56.29
Collet Stock = LL + CF + CD – SL x – AL y
Collet Stock = 100 + 5 + 30.15 – 48.45 – 56.29
Collet Stock without Boost = 30.41mm
Note: If the calculated collet stock is a negative number and the last
straight is less than 2D, then only add enough material to make the
last straight 2D. If the calculated collet stock is a negative number
and the last straight is greater or equal to 2D, then no additional
collet stock material is required.
Theoretical tube length
The theoretical tube length is the sum of the three main components:
clamping stock, component(s) stock, and collet stock:
Theoretical tube length formula:
Clamping stock + component(s) Stock + Collet Stock
From the sample data:
•
Theoretical tube length (with boost) = 96.63 + 509.27 + 106.41
•
Theoretical tube length (with boost) = 712.31mm
•
Theoretical tube length (without boost) = 96.63 + 509.27 + 30.41
•
Theoretical tube length (with boost) = 636.31mm
So what’s stopping you?
As process consultant, AddisonMckee is often asked to advise
clients on the amount of material required to bend a component or
series of components.
To facilitate a smooth ramp-up to production, AddisonMckee will
typically play it safe in arriving at its calculations. This approach
is obviously the safest way to avoid the unthinkable scenario of
the consultant having to go back and tell the client that the twenty
bundles of tubes he just purchased are an inch too short.
However, and this is key, there still continue to be many examples
where the initial tube length is accepted as gospel and never
re-evaluated. With re-evaluation the cost savings can be very real
and, just as importantly, very easy to make.
Ultimately, though, the best money-saving strategy is the most
basic of all: using your eyes. Simply look at the ‘off-fall’ coming
from the first clamped end and ask yourself: “Does it need to be
this long?”
Run the bender to the end of the last bend, pause it, and look again.
Then ask yourself “What’s stopping me from shortening the tube?”
The answer may well be obvious and very simple.
Nothing.
Forming better strategies for all its
customers
The fortunes of AddisonMckee itself have certainly taken a turn
for the better in recent months as the market climbs out of
recession.
New ownership has galvanised the company by introducing a
number of measures to ensure a smoother ride for all its customers,
in, among others, the automotive, aviation, truck and shipbuilding
industries.
First and foremost, while the company remains a truly
global concern with partners all over the world, in response
to overwhelming demand from its European customers,
AddisonMckee has restored the manufacturing facility at its
HQ at Bamber Bridge in the UK, a move that underscores the
company’s commitment to its European partners not least by
significantly reducing costs.
Figure 6