This is some of what I have learned since becoming a member of this
newsgroup almost a decade ago, when it was fun to post and learn about
things actually used on the shop floor. I thought I would take some
time to reflect on some of the things I have learned and teach on a
daily basis, helping people out, making a living by working hard and
realizing the mistakes that I have made applying cutting tools and how
it can be turned around into showing machine shops how NOT to make
those mistakes and and go through that pain.

A Lathe Cutting Tool Test is complete. The same style of insert geometry was used so as the same holder was used during the test. Brands, Grades and Chipbreakers were changed. The results are documented. With the benchmark set forth from the current tool, it is now time to calculate the potential overall cost savings of the new tool.

The initial findings are the new insert costs $1 more than the current insert AND the new insert gets 50 parts LESS than the current insert. Should you stop calculating the test results due to what appears to be an obvious waste of test time and stay with the current insert or should you continue on taking all aspects of the test into consideration?

Believe it or not most shops will ask to stop right there due to the obvious higher cost of the tooling involved. But they miss the point of calculating the Time Factor and how it applies to machine capacity.

Let’s continue just to see what was learned during this test.

These 5 factors stay the same regardless which tool is used: 1. Shop Rate is $60 per hour for this test. Easy to figure $1 per minute that way. 2. There are 6,000 parts on this job. 3. The insert makes 1 Z-Axis cutting motion that is 7-1/2” in length. 4. It takes a total of 2 minutes on average (downtime) to properly index the insert when needed. 5. Both inserts have 2 cutting edges.

Here are the Variables that need to be calculated: Current Insert Cost is $7 each Test Insert cost is $8 each

Current Insert lasts for 250 parts Test Insert lasts for 200 parts

Current Tool is turning at 1500 RPM and .005” IPR Feedrate Test Tool is turning at 2000 RPM and .0075” IPR Feedrate

Let’s see if the shop should stay with the current insert or proceed to use the new insert.

Using the current insert to make 6,000 parts will consume 24 cutting edges, which is 12 inserts, which has a total cost of $84. Tool cost per Part is $.014 Using the new insert to make 6,000 parts will consume 30 cutting edges, which is 15 inserts, which has a total cost $120. Tool cost per Part is $.020 New Insert shows a savings of (negative) -$36 or $.006 per Part.

Current Insert was feeding at 7.5 Inches per Minute, taking 1 minute of cycletime. Adding $1.000 of cost to the part.

New Insert was feeding at 15 Inches per Minute, taking ½ minute of cycletime. Adding $ 0.50 of cost to the part.

Running Total for the Cost Per Part for Tooling and Cycletime is: Current Insert $1.014 per part. New Insert $0.52 per parts. New Insert showing a savings of $0.494 per Part.

Downtime to Index Insert: Current Insert consumes 48 minutes of indexing time. $48.00 cost, $0.008 per Part. New Insert consumes 60 minutes of indexing time. $60.00 cost, $0.010 per Part.

Running Total for the Cost Per Part for Tooling,Cycletime and Downtime is: Current Insert $1.022 per part. New Insert $0.53 per part. New Insert showing a savings of $0.492 per Part.

Current Insert will complete the job with a total cost of $6,132. New Insert will complete the job with a total cost of $3,180. Dollar Amount Saved on THIS job with the New Insert is $2,952.

Time Consumed using the Current Insert is 6,048 minutes, 100.8 hours. Time Consumed using the New Insert is 3,060 minutes, 51 hours.

The next job could be running 49.8 hours sooner in the work schedule, which if the shop was running 1 shift with overtime would be 1 week sooner. Plus the overtime wage was calculated into this test so the savings would be even greater if indeed this was the scenario.

We can debate Rapid Movement Times, other little tidbits of idiocy also, but the point I’m trying to make is the tooling cost is minimal compared to time wasted in any way it is wasted. But the main culprit shops target is the tooling. The reason being is the Owner sees an invoice for $120 instead of the $84 he is used to. The Owner, or even worse the Controller/Accountant doesn’t see the chip bin fill up faster or the machine open up quicker for the next job to start.

With this NEW FREE OPEN MACHINE CAPACITY working for them, the shop may not need to purchase another piece of machinery (from China, Japan or Germany as is in most cases today) that cost in excess of $250,000 or more to be competitive. They can compete on Quality and Delivery while keeping their costs fair to be more profitable for their future and their workers future.

Thanks for reading this. JR

A Lathe Cutting Tool Test is complete. The same style of insert geometry was used so as the same holder was used during the test. Brands, Grades and Chipbreakers were changed. The results are documented. With the benchmark set forth from the current tool, it is now time to calculate the potential overall cost savings of the new tool.

The initial findings are the new insert costs $1 more than the current insert AND the new insert gets 50 parts LESS than the current insert. Should you stop calculating the test results due to what appears to be an obvious waste of test time and stay with the current insert or should you continue on taking all aspects of the test into consideration?

Believe it or not most shops will ask to stop right there due to the obvious higher cost of the tooling involved. But they miss the point of calculating the Time Factor and how it applies to machine capacity.

Let’s continue just to see what was learned during this test.

These 5 factors stay the same regardless which tool is used: 1. Shop Rate is $60 per hour for this test. Easy to figure $1 per minute that way. 2. There are 6,000 parts on this job. 3. The insert makes 1 Z-Axis cutting motion that is 7-1/2” in length. 4. It takes a total of 2 minutes on average (downtime) to properly index the insert when needed. 5. Both inserts have 2 cutting edges.

Here are the Variables that need to be calculated: Current Insert Cost is $7 each Test Insert cost is $8 each

Current Insert lasts for 250 parts Test Insert lasts for 200 parts

Current Tool is turning at 1500 RPM and .005” IPR Feedrate Test Tool is turning at 2000 RPM and .0075” IPR Feedrate

Let’s see if the shop should stay with the current insert or proceed to use the new insert.

Using the current insert to make 6,000 parts will consume 24 cutting edges, which is 12 inserts, which has a total cost of $84. Tool cost per Part is $.014 Using the new insert to make 6,000 parts will consume 30 cutting edges, which is 15 inserts, which has a total cost $120. Tool cost per Part is $.020 New Insert shows a savings of (negative) -$36 or $.006 per Part.

Current Insert was feeding at 7.5 Inches per Minute, taking 1 minute of cycletime. Adding $1.000 of cost to the part.

New Insert was feeding at 15 Inches per Minute, taking ½ minute of cycletime. Adding $ 0.50 of cost to the part.

Running Total for the Cost Per Part for Tooling and Cycletime is: Current Insert $1.014 per part. New Insert $0.52 per parts. New Insert showing a savings of $0.494 per Part.

Downtime to Index Insert: Current Insert consumes 48 minutes of indexing time. $48.00 cost, $0.008 per Part. New Insert consumes 60 minutes of indexing time. $60.00 cost, $0.010 per Part.

Running Total for the Cost Per Part for Tooling,Cycletime and Downtime is: Current Insert $1.022 per part. New Insert $0.53 per part. New Insert showing a savings of $0.492 per Part.

Current Insert will complete the job with a total cost of $6,132. New Insert will complete the job with a total cost of $3,180. Dollar Amount Saved on THIS job with the New Insert is $2,952.

Time Consumed using the Current Insert is 6,048 minutes, 100.8 hours. Time Consumed using the New Insert is 3,060 minutes, 51 hours.

The next job could be running 49.8 hours sooner in the work schedule, which if the shop was running 1 shift with overtime would be 1 week sooner. Plus the overtime wage was calculated into this test so the savings would be even greater if indeed this was the scenario.

We can debate Rapid Movement Times, other little tidbits of idiocy also, but the point I’m trying to make is the tooling cost is minimal compared to time wasted in any way it is wasted. But the main culprit shops target is the tooling. The reason being is the Owner sees an invoice for $120 instead of the $84 he is used to. The Owner, or even worse the Controller/Accountant doesn’t see the chip bin fill up faster or the machine open up quicker for the next job to start.

With this NEW FREE OPEN MACHINE CAPACITY working for them, the shop may not need to purchase another piece of machinery (from China, Japan or Germany as is in most cases today) that cost in excess of $250,000 or more to be competitive. They can compete on Quality and Delivery while keeping their costs fair to be more profitable for their future and their workers future.

Thanks for reading this. JR