As Director of Technology and Industry Research for PMPA, Miles brings 38 years of hands-on experience in areas of manufacturing, quality and steelmaking. He helps answer "HOW?","WITH WHAT?" and "REALLY?"
Photo Credit: "Acme Gridley Multiple Spindle Bar Machine Manual," First Edition 1961 page C11.
There are many different ways part length can vary when using a cut-off tool on multi- spindle automatic screw machines. Here are some of the major ones grouped into a rough classification by where the cause exists.
The cut-off tool itself:
Tool is dull
Tool is improperly ground (point angle too large)
Tool loose/improperly inserted into holder
Tool blade is too thin
Cut-off tool is hitting while in high speed
Cut-off tool being hit by die head or chasers
Toolholder itself is loose
Toolholder is hitting work spindle
Toolholder is hitting tool post
Toolholder is warped or bent
Toolholder is worn
The work spindle:
Spindle has end play
Spindle has worn bearings
Spindle carrier has end play
Index lock pin spring is broken
Finger holder not adjusted properly
Broken pins or fingers in finger holder
Feed tubes bent or beat up
Wrong stock feed cam—overfeeding stock will cause bounceback from stock stop resulting in short part
Incorrect collet tension
The cross slide:
Cam is loose
Cut-off cam is too large and causes too much feed
Cam drum is loose
Stock pushed back into collet by drill (dull drill pushing stock rather than cutting chip)
Stock pushed back into collet by reamer
Face-off tool is loose
Face-off tool is dull
Face-off toolholder is loose
Die head pulling stock out of collet, making part long
Part length can occasionally go awry when using cut-off tools on automatic screw machines.
This post lists more than 30 reasons that I can think of. What did I miss?
Lesson 1: It’s not one thing. There is no magic bullet. There is no miracle pill. Machining is a system. Understand the system, and address system weaknesses.
Stop looking for magic answers. There is seldom a single change you can make that will optimize your process. You must consider the entire system. I took in every technical session while I was there. I expected to be told that “Whatever it is I’m showing you” is the answer to your machining problems. I was not told that at all. In all the sessions, the focus was on optimizing and understanding the interactions of the system and its components, which was refreshing.
Lesson 2: In our business, success is defined by sustainability, not lowest price. By sustainability, I do not mean “greenwashing.” To be sustainable, a company must learn to solve problems. Problems unsolved have the potential to bring your company down.
How to become more sustainable:
Solve problems first.
Solve the problem for good.
Understand that the lowest cost over the long term is not the lowest price over the short term.
Spend less time on maintenance by planning it.
Spend more time on production.
Spend more time on innovation.
This is why we have root cause analysis. We should only have to solve a problem once. Assure organizational learning takes place. And move forward.
Lesson 3: Pay attention to energy. This one was a complete surprise. Who knew that 37 percent of machine tool energy consumption is related to coolant and lubricant? Through-tool coolant typically runs at a rate of about 1 liter per minute (about a quart here in the U.S.) Traditional flood coolant is typically 18 liters per minute. (That’s about a 5-gallon bucket.) And the through-tool coolant is applied exactly where it is needed.
I’m not quite convinced that MQL is the answer for production machining, but I saw some demonstrations that continue to make me think.
On another note, typically utilities run from 6 to 10 percent of sales dollars in our shops. We’ve seen estimates that shop lighting can run as much as 37 percent of the electrical consumption in Warehouses and light manufacturing shops. Even if you cut that in half, it is probably wise to evaluate your current shop lighting. We can talk about compressed air another time. If you hear compressed air in your shop, you are listening to dollars floating away.
Lesson 4: Conventional milling equals conventional rubbing. All of the programs on milling at Horn showed climb milling as the preferred practice. I’m not going to pretend expertise here, but what I thought I knew is no longer what I think I ought to know in regards to cutter rotation and material feed. Climb milling is the preferred way in modern shops today.
Lesson 5: Be optimistic. Horn is expanding again. Another new building was being built down the road. Why be optimistic? How can you be optimistic? It is easy to be optimistic if you are a private company. If you believe in continuous improvement, then you want tomorrow to be better than today. Today is today, but our way is the future. Our way is going forward. Do it today, for tomorrow. Can’t argue with that. That is why Horn has a class of apprentices in development. How about you?
Bonus Lesson 6: “The Best People are the Basis of the Future.” Lothar Horn shared this thought with me in a private conversation. It really fit hand in glove with Horn’s optimistic approach to the future. By training the people and making available opportunities to learn and grow, the company is preparing its team for an anticipated, but not yet understood, future.
“There is a continuous demand to upgrade our tools. We can only meet that demand by upgrading the skills of our workforce and the technology they apply.”
When that future arrives, they know they have done their best to be prepared for that day and its challenges.
That future will arrive. It arrives every day. What have you done to prepare your shop for the future that will soon arrive?
“Machining for Hobbyists, Getting Started” Is a surprisingly complete and easy to understand book that can be used to supplement training on the job for beginners and a nice reference for those with a year or so on the job. Machining and measurement principles and techniques are clearly explained.
I was genuinely surprised to find some great nuggets, such as “The Basic Nomenclature of Measurement,” which clearly defines nominal size, allowance, limits, tolerance, basic size, unilateral tolerance; bilateral tolerance, precision and accuracy, in a little over a page.
The book includes nice graphics, sample calculations, and well done explanations on how to read a micrometer, vernier, as well as tables with feed and speed data for various types of materials for specific machining operations. It’s focused coverage of the essentials.
Do not confuse this book for a hobbyist project catalog. It contains clear and understandable text that explains the “how, why and what” of machining and the use of tools of our craft, and has nice photos, too. What I like the most is how the author really distills the information down to useful essentials and makes them understandable.
In 2009, while two of the three bankrupt-thinking Detroit firms were using the government to bully their way through bankruptcy, running roughshod on their suppliers and creditors, I wrote a piece about “The New Domestics.”
Here are a few points that I made in that article:
More than 70 percent of the value added in a new car is provided by the suppliers, not the assemblers
More than 300 companies have created jobs in Ohio as a result of the state’s “New Domestic” auto industry
Honda has plants or major operations in Alabama, California, Connecticut, Colorado, Georgia, Indiana, Iowa, Michigan, New Jersey, North Carolina, Ohio, South Carolina, Tennessee and Texas
Mercedes has a plant in Alabama, too
BMW has a plant in South Carolina
Volkswagen has broken ground for an assembly facility in Chattanooga, Tennessee (it’s been making cars since 2011 and employs 2,000 people)
So what is an American car? One made by my friends and neighbors, made from materials and parts purchased locally, one that the first digit of the VIN is a 1, and one that has more than 50 percent “domestic content.”
What is the U.S.’s leading auto exported abroad? Read the surprising answer here.
Postscript: This is not to diminish the role of Canadian manufacturers, nor their vehicle assembly plants. PMPA members in Canada produce high volumes of high technology system parts for the automotive markets—fuel injectors, anti-lock brake parts, fluid power system components and much, much more. But the irony of the whole Ford “wrap ourselves in the flag while we really export your jobs” marketing is the “driver” behind this post.
Chemical manufacturers, importers, distributors and employers are now required to provide a common approach to classifying chemicals and communicating hazard information on labels and safety data sheets. The June 1 deadline was established when OSHA aligned its Hazard Communication Standard in 2012 with the global standard for chemical product labeling.
Chemical manufacturers and importers must provide a label that includes a signal word, pictogram https://www.osha.gov/dsg/hazcom/pictograms/index.html, hazard statement, and precautionary statement for each hazard class and category. Beginning in December, distributors may only ship containers labeled by the chemical manufacturer or importer if the labels meet these requirements. Until then, your shop will likely see containers with old or new pictograms and information.