The Plus-membrane [+]

Facts about SPV Spintec’s milling membrane – The Plus-membrane [+]

SPV Spintec’s hexagonal milling membrane permits tough, vibration free milling. A highly stable tool anchorage make it possible to machine at greater feed rates and with greater axial and radial depths of cut then normally recommended.

Limitations of conventional hydro chucks

The limitation in machining with hydraulic chucks has frequently been the use of recommended cutting data for heavy duty milling.

Customers have often been obliged to purchase specially shortened hydraulic milling chucks with increased torque when they have had the need to remove a large amount of material in a short amount of time.

We have eliminated this limitation and offer our customers the opportunity if using our developed hydraulic milling membrane for both milling and other operations, resulting in a better overall economy.

Development

A calculation and simulation of loading cases using the Finite Element Method (FEM) from 3D-models was done in collaboration with Mälardalens University College in Eskilstuna. This was to verify the results offered by the new design and to make a comparison with the traditional cylindrical membrane design in hydro chucks.

Testing

A trial was done in the spring of 2003 at SECO tools in Fagersta, Sweden to attempt to verify any limits there might be on cutting data. An extract from the test report (P-1006, 2003-04-29 at SECO, Fagersta) shows the following.

• Test sample:
  Hydro chuck HCF+ with hexagonal membrane
• Machine tools:
  Solid 3-blade carbide metal cutters made by Jabro, with Tribon coating.
  Dimensions: Ø10 mm, Ø12 mm and Ø20 mm.
• Work piece material:
  Square bar, 75 x 75 mm made from head treatable steel SS2244-05, hardness 270 – 315 HB.

Test summary

The results show that the hydro chucks equipped with a hexagonal membrane can manage up to twice the recommended cutting depth (both radial and axial) without tool chipping or vibrations that affect the surface finish. In practice, this means that possible swarf yield has been multiplied by four.

Specifications

Coarse slab milling with rotational speed and feed rate to Jabro’s recommendations:
Recommended depth of cut:
axial: 1 x tool diameter
radial: 0,4 x tool diameter
Results in a chip area of:
1 x D mm x 0,4 x D mm = 0,4 x D mm²

Coarse slab milling with rotational speed and feed rate to Jabro’s recommendations:
HCF+ tests with twice the recommended depth of cut, axial and radially.
Results in a chip area of:
1 x D mm x 0,4 x D mm = 0,4 x D mm²