Product category:
CNC lathes
News Release from: Yuasa Warwick Machinery | Subject: Takamaz XD-8 twin-spindle CNC lathes
Edited by the Manufacturingtalk Editorial
Team on 09 December 2002
Twin spindle CNC lathes improve quality,
accuracy
Acquisition of a pair of twin-spindle CNC lathes has brought significant improvements in production flexibility, quality, accuracy and lead time at Floform, Welshpool.
Acquisition of a pair of Takamaz XD-8 twin-spindle CNC lathes from Yuasa Warwick Machinery has brought significant improvements in production flexibility, quality and lead time at Floform, Welshpool The main products machined on the lathes are a family of bi-metal, stud-type components for power switching electronics applications
This article was originally published on Manufacturingtalk on 31 May 2001 at 8.00am (UK)
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Recently the company, which is part of the privately owned Hasgo group, has absorbed Tower Forged Products, a specialist producer of cold formed industrial fasteners.
A Floform speciality is cold formed bi-metal work.
As well as the stud-type parts processed on the Takamaz machines, which are a combination of copper and steel, the company also manufactures millions of copper-cored, Inconel-sheathed spark plug electrodes.
Components are normally manufactured using wire or bar up to 40mm diameter as the starting point, and the company has facilities to finish components up to 100mm diameter using its orbital forging press.
David Richards, senior development engineer at Floform, commented, "Cold forming is by nature a high volume production process.
However, for some years we have used CNC and cam-actuated machining to perform secondary finishing operations.
In the case of the studs now processed on the Takamaz machines, these operations comprise facing of the surface to a flatness of 10 microns, grooving of the steel rim, trimming to length and thread generation." In appearance, the studs are rather like a short hexagonal headed bolt with an over-large head.
Each is manufactured from a cylindrical slug which has a thin washer-like steel ring brazed to the top.
The cold forming process generates the hexagonal head and extrudes the stem.
There is a large family of around 50 small studs and ten types of large stud.
These have significant detail differences; the stem diameter is one source of variation while some studs have a raised plinth on the head and others require a recess.
Some also require a groove to be machined in the steel ring while others require both the top and bottom faces of the hexagonal head to be machined.
"Although total annual production is measured in millions, each individual stud type is produced in quantities of a few hundred thousand, spread over twelve months," Richards explained.
"Although we have machined the components on cam-controlled machines for some years, the lengthy set-up time on this type of equipment, coupled with age-related reliability problems, undermines the economics of production; especially as, nowadays, our customers tend to require smaller batches." This led Floform to examine the use of CNC equipment to machine the components.
The company is no stranger to CNC turning and already operates a number of manual and automated cells for various types of component.
Richards was therefore well placed to define the requirement and assess the alternative solutions on offer.
"I have to say that the Takamaz XD-8 satisfied virtually every one of our selection criteria," he said.
"We wanted a single-source solution, so the fact that the machine is equipped as standard with work handling made it an obvious contender.
It is also the right size and well priced, even with the vibratory bowl feeders and the initial turnkey applications engineering package included." The Takamaz XD-8 is a twin-spindle CNC lathe with high speed servo gantry loaders (75m/min) serving each spindle.
Tooling is carried on a central platen (optionally a 6-station turret).
Users have the option of feeding components in from both sides or one side for single operation machining, or feeding components from one side for sequential front- and reverse-end machining operations on every component.
In the latter case, as at Floform, a transfer station is incorporated above the platen.
Both machines are set up for a similar sequence of operations.
Components are orientated in the bowl feeder and fed onto an input conveyor that aligns the parts using the flat sides of the hexagonal head.
The pick-and-place gantry for Spindle 1 then grips the component by the head and places it in the collet where it is held by the stem.
The copper top face is machined using polycrystalline diamond (PCD) tooling and a carbide grooving tool is used to machine the steel rim.
When machining is complete, the XD-8's C-axis ensures that the component is available for picking in the same orientation as it was when placed.
The Spindle 1 gantry then moves the component to the transfer station where it is picked by the Spindle 2 gantry, gripping on the stem.
It is placed in a purpose-made, hexagonal collet that is aligned identically with Spindle 1 to ensure accurate placement.
The stem is then cut to length using a carbide part-off tool and the thread is produced using a twin-roller thread rolling head.
The finished component is off-loaded by the gantry and placed on the output conveyor.
'Part present' detection is included on the gripper for Spindle 2.
"At the moment we are unable to roll threads on the Takamaz used for our larger components, due to the large diameter of commercially available radial rolling heads needed for threads up to M20," Richards explained.
"However, we are confident that we can achieve a solution." Improvements have also been made on cycle times.
On the machine that processes small studs, the gantries need to operate at the maximum speed of 75m/min to keep up with machining whereas on the machine processing larger studs, a slower speed is adequate.
Bowl feed capacity is sufficient for up to twelve hours of continuous operation.
"The Takamaz machines have proved to be very satisfactory performers Richards confirmed.
"Our requirement from Yuasa Warwick Machinery was for three of the small stud component types to be engineered as turnkey applications and for the capability of the bowl feeds to be satisfactorily demonstrated.
This they did very well.
Following on from their very good training we have had no trouble in developing additional applications as required.
From a quality standpoint we have been able to meet flatness and finish tolerances with relative ease, while PCD tool life is excellent." One bonus arising from the new set-up is the capability of the vibratory bowl feeders to handle slightly oily components straight off the cold forming presses.
These previously had to be degreased prior to machining.
In addition, the swarf handling has improved immeasurably - Floform processes 99.95 per cent pure, high conductivity copper which is stringy and sticky to machine.
On the old cam machines it was necessary to sort finished components from the swarf, but complete separation in-process is now assured.
In addition, the swarf output from the screw conveyor is easy to load into the company's swarf compaction machine.
Richards concluded, "It is the flexibility and accuracy of the machines that provides the principal advantage.
We have machined batches as small as 500-off which would previously have been unthinkable.".
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