Tuesday, March 31, 2015

5% Back Amazon Credit Card


Wednesday, November 28, 2012

Skills Gap Impacts Machine Tool Sales?

Interesting quote from the Front Range Community College blog:
“I tell the machine tool salesmen that I’d love to buy a new machine from them, but only if they can bring me the résumés of three qualified machinists,” says Bob Bergstrom, president of St. Vrain Manufacturing in Longmont. St. Vrain Manufacturing is a precision machine shop serving high tech, aerospace, telecom, and other industries.

With CNC, CMM, CAD/CAM and other new technologies, modern machining has transitioned from an art to a digital-based science. The one major knowledge gap that has not been digitized is the selection of speeds, feeds and depths of cut which have been described as:

“...often ad-hoc and empirical. Process parameters, such as machining speeds, feed rates, and tool selection, are typically chosen by costly, trial-and-error prototyping, with the resulting solutions often sub-optimal.”[1]

“In CNC machining, usually the programmer programs speeds and feed rates that are as maximally tuned as calculations and general guidelines (with charts and formulas) can supply. The operator then fine-tunes the values while running the machine, based on sights, sounds, smells, temperatures, tolerance holding, and tool tip lifespan.[2]

[1] http://en.wikipedia.org/wiki/Speeds_and_feeds, page last modified on 31 March 2011 at 05:43

[2]  Advancing Manufacturing Summit 2, May 20, 2003

Saturday, May 26, 2012

Regrind Endmills?

Should you regrind/resharpen your carbide endmills? Here's a section from the Dormer Regrinding Guide with our comments in red italics:


Reduction in Diameter 
A loss in diameter occurs when grinding the periphery of the primary land. This 
progressively impacts the end mill’s deflection capacity when under load. Compare 
Figs. 1 and 2.
The change in diameter changes the tool point frequency much like different diameter tubes of a wind chime produces different tones.

Reduction In Radial Rake Angle
An end mill must possess a rake angle that is suitable for the material being machined.
After each regrind there is not only a reduction in diameter, but also a subsequent
reduction in the radial rake angle. This, together with the corresponding, if slight change,
in helix angle significantly affects the efficiency of the end mill. Compare Figs. 1 and 2.
Face rake angles can be re-established by regrinding the flute face of the end mill.
Reducing the rake angle increases the cutting forces and the amplitude of the deflection of the tool point, changing its frequency.

Increase In Secondary Land Width
The secondary land width increases substantially as a result of regrinding, which in turn
increases regrinding time and cost. Compare Figs. 1 and 2.

Reduction In Flute Depth
As a consequence of reducing diameter, there is a corresponding reduction in the flute
depth. Because of the subsequent impact on chip evacuation capabilities it can force
the utilisation of feed rates that would be considered far less efficient. Compare Figs. 1
and 2.

Saturday, May 5, 2012

Cutting Tool Cost Comparison Utility

When the Boeing Research and Technology group of St. Louis works with Boeing suppliers to refine their machining processes, the researchers advise these shops to consider more than just the purchase price of the tool. A cheap tool can be expensive, if it limits the productivity of the machine...read more
For your convenience, you can download Boeing's Powerpoint slide and Excel file here.

Tuesday, April 3, 2012

Counting Tray for Small Fasteners and Helicoils

When I had a distributorship we sold a lot of small fasteners. Socket head cap screws, set screws, nuts, washers and helicoils. As a service to our customers we would break boxes and sell them only what they needed. No need to buy 100 when you only needed 12 for the job. Counting them out was a chore. We set up a workstation just for the small sizes with a counting scale. But the scale didn't work with tiny fasteners, like 4-40 helicoils. If we only had one of these, the job would be much easier. For years I tried to talk my pharmacist out of one, but never could. Now you can buy one: