Product category:
Pneumatic Actuators, Motors, Accessories
News Release from: Festo | Subject: Fluidic Muscles
Edited by the Engineeringtalk Editorial
Team on 19 March 2003
Shear muscle force crops copper
Novel Fluidic Muscles from Festo have been deployed in a high force application to assist with the manufacture of electrical starter motors for buses and trucks.
Award-winning Festo Premier Stockist Blackson and Kenridge has shown why it achieved the Festo accolade of Premier Stockist of the Year for 2002 The company is behind the ingenious application of the acclaimed Festo Fluidic Muscle to deliver forces over 30,000lbf/in2 to crop copper conductors in a production machine designed and built by Hamlyn Engineering of Middlesex
Rather than use six 125mm diameter cylinders of 50mm travel arranged in a vertical stack and driven in unison to operate the rotary guillotine mechanism, Blackson and Kenridge recommended using eight of the new Festo Fluidic Muscles, each only 40mm in diameter.
Rather than using air to drive a piston, the fluidic muscle deploys a mesh of interwoven fibres surrounding a hollow flexible core.
Introducing air to the core deforms the structure, generating movement and an axial force.
The muscle offers performance advantage in terms of immense power, along with smooth operation and exceptionally light weight.
A muscle weighs just one tenth that of a metal cylinder of equal inner diameter, yet generates forces typically ten times as great.
The customer's end product is a starter motor used in trucks and buses.
During the motor production process, 27 strips need to be cut to length in situ.
For speed and consistency, cropping all 27 conductors simultaneously was the optimum solution, providing the design team could develop a system capable of applying the force and control, as cutting copper requires between 22,000 and 30,000lbf/in2 force, and the combined cross-sectional area of the 27 conductors is 1.125in2.
Hamlyn, along with sister company Camberley Automech, designed a bar cropper machine - a rotary guillotine mechanism comprising two circular die with 27 wire eroded holes to take the copper strips.
The die has D2 hardened cutting faces.
Besides the force consideration, a second factor for specifying the pneumatic actuator is the linear travel needed.
27 equispaced holes equate to an angular travel of 13.333 degrees.
Rotating the die through a 15-degree angle would ensure a full cut - which demanded a travel of 30mm.
The economics were also in favour of the Fluidic Muscle solution.
At around GBP 230 each, standard 125mm cylinders would cost approximately GBP 1400.
The minimum axial deflection of a 40mm diameter fluidic muscle is one quarter of its length.
So to achieve the 30mm movement, muscles of 120mm length were required.
These cost just GBP 74 each - a total of GBP 592 - and an immediate cost saving of almost GBP 800.
As head of the design team, Mac Ghadially encountered another advantage of the muscles during the machine build process.
"They have superb accuracy upon return in the relax mode", he says.
"This attribute was on my wish list because it eliminates the need for a stopping cylinder to reposition the cutter at the start point, but I didn't expect to get it from the muscle".
The Festo fluidic muscle offers a sound yet innovative commercial solution in many applications.
It's also one that allowed Ghadially to meet his initial goal of keeping the bar cropper machine simple and cost-effective by eliminating the need for control electronics.
"It is a completely pneumatic solution with no need for sensors or PLCs", he concludes. Request a free brochure from Festo ...
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