ER Chuck Toolholder and Shrink Fit Toolholder Case Study

ER chuck vs shrink-fit holder case study.

Comparison of tool life, cutting ability, and surface finish.

CONCEPT
Techniks recently performed internal tool trials to assure compliance with its standard for high quality tool holders and to create a benchmark of comparison between tool holding technolgies. This test evaluated an ER collet chuck versus a shrink-fit tool holders under "real world" conditions.

TEST CONDITIONS

This trial was performed on a CNC Vertical Machining Center with a CT 40 taper. Identical tool paths, spindle speeds, feed rates, material conditions, holding devices, coolant delivery, end mills and chip loads were utilized to isolate the performance of these tool holding technologies. The test cuts were in 4140 Prehard (30-32 Rc) using 3 flute uncoated carbide center cutting end mills. The identical tool paths involved a variety of cutting directions.

TEST RESULTS

Tool Life
The most significant comparison between these tool holding technologies is in the area of tool life. The end mill in the shrink-fit toolholder showed dramatically less wear (photos top) compared to the end mill used in the collet chuck (note the fractured surface).

In our tests there was significant fretting on the taper of the ER collet chuck tool holder while there was virtually no fretting on the shrink-fit holder (visible in photo above). This was attributed to the superior wear characteristics of H-13 tool steel over 8620.

Our results back up other reports that shrink-fit allows 4 to 7 times the tool life of other tool holding technologies.

Cutting Ability
During our four machining test passes of .125” depth of cut, the shrink fit tool holder required less spindle load than the ER collet chuck tool holder. The increased rigidity of shrink-fit created a more balanced chip load during cutting. This was observed in a better machining sound.

Surface Finish
The improved concentricity and increased rigidity of the shrink fit tool holder produced a moderate improvement in surface finish of the test piece compared to the test piece machined with the ER collet chuck.

CONCLUSION
While both technologies have their place, machining using shrink-fit is a significant improvement over ER collet chuck technology. Shrink-fit has advantages in tool life, cutting ability, surface finish, and produces less wear-and tear on the toolholder shank and spindle bearings. Concerns regarding shrink-fit tool changes have been resolved by the new generation of induction heat shrink-fit machines that provide extremely fast tool changes and are safe to operate.

The advantages to a production machining operation using shrink-fit are outlined below.

FASTER Spindle speeds and feeds are increased to reduce cycle times. Shorter cycle times result in increased manufacturing capacity improving your R.O.I.

BETTER Concentricity of .0002” permits better balanced chip loads so machining is more accurate. This improved part finish and quality increases customer satisfaction with your product.

CHEAPER Tool life is extended by as much as 700% dramatically impacting your tooling budget. Additionally, fewer tool changes results in labor savings and reduced machine down-time. The natural balance of the shrink fit tool holder and even chip loads decreases the wear and tear on spindle bearings. Longer spindle bearing life reduces maintenance costs and keeps machines productive longer.

We're here to answer your tough questions about toolholders. Call us 8:00 to 5:00 EST at: (800) 597-3921, or click the link to find out more about Shrink-Fit Toolholders.

Chart shows the effect T.I.R. has on tool life

Chart shows effect of T.I.R. on tool life.

Toolholders make the
tool life difference!

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