Extruder Screws - Twice as Fast
In today's injection mold industry, designs of multi-segmented Extruder Screws are more complexed than ever,
and so are the demands on how these screws are to be manufactured. Ideally removing the maximum amount of
material in the shortest possible time, while still leaving a high quality surface finish thus eliminating
not only a costly but, very time consuming grinding operation.
Now those previously unattainable goals have all come together into one advanced machine from Leistritz,
multipurpose machining center line. This CNC controlled multipurpose machine combines Whirling
all on a single space saving vertical bed design.
Ralph Wehmann, National Sales Manager of machine tool sales at Leistritz Corporation, describes the advantages
of this multipurpose machine: "Whirling is the fastest machining method for producing extruder screws, and if
you compare whirling with milling, there is a big improvement in surface finish due to the smooth tangential
cutting action you get by whirling." By improving profile finish, there is an elimination or at least a reduction
in the need to grind or hand polish. Since these operations are normally very time consuming, the cost savings
can be tremendous.
Whirling however, is not capable of cutting all profiles such as, screws with a very high helix angle or
profiles with square flanks. Screws with these characteristics are better off milled. So which method is better
for producing extruder screws? The answer is simple says Wehmann, "The Leistritz LWNM multipurpose machine, it
was developed with extruder screws in mind combining the speed and metal removal of whirling along with the
versatility of milling, in effect what you have is a multiple machine in one."
Wehmann also states that the LWNM Machining System allows the manufacturer to do nearly all the manufacturing
operations to the screw in just one chucking. In addition to Whirling and Endmilling, Sidemilling operations
can also be performed on splines, found on many of today's feedscrews.
Engineers at Leistritz have developed an efficient system in order to change cutting heads, it can go from
Whirling to Milling in a matter of minutes. Traditionally feedscrews required multiple setups to perform
many operations, usually on a variety of machines, but with the Leistritz system can this now be completed in
just a single setup, with one LWNM machine. Another important benefit resulting from machining all operations
in one chucking and reducing part handling, is that the accuracy of any part becomes much greater.
The economics of the Leistritz LWNM multipurpose machine are such that, no longer does a manufacturer need to
have three separate whirling, milling and turning machines. They can get the same performance of all three
machines in one, along with a reduction of manpower and shop floor space savings. But the real advantages
come from the time savings generated by the speed of whirling and having the ability to quickly go from a
whirling mode to milling or turning operation. Tests show that 2 to 3 times faster production rates can be
expected from just a single Leistritz LWNM Whirling
, and Turning Machine