“By controlling the important variables, dimensional changes in heat treatment can be controlled.” Patrick McKenna
Variability is the enemy in our precision machining shops, and reducing variability is a key to sustaining our businesses and improving our capabilities.
When I talk about statistical process control with someone, I listen closely to see if they are focused on the average (where the process is performing) or the standard deviation ( how the process is performing.)
If they are fixated on the average, I know I need to look at the data myself. On the other hand if they are talking about standard deviations, I generally take their word on the data…
In the latest issue of Production Machining Magazine, PMPA Technical Member Patrick McKenna from Nevada Heat Treating Inc., and Daniel Herring, the Herring Group Inc. teach a nice class on how to reduce process variation in heat treat to minimize the post heat treat variability that all of us face.
This is important if we are not to waste our production time trying to remove excess material because we left too much stock for cleanup, or worse, finding the parts have shrunk in some critical dimension, rendering all of the parts ‘scrap.’
This article lists 9 variables NOT in control of the heat treater, and 14 that are under their control (furnace temperature uniformity, load configuration) or shared by the customer ( process selected, batch size, part size).
Not every order we produce is part of a long running job where we can control every input variable, but this piece does a great job of providing sensemaking on what can be a complicated and confusing subject.
I predict that you’ll keep this article in your “great to know” file.
Author: Miles Free
The link in this post will take you to a table of the Top 10 Training Citations by OSHA for the Precision Machining Industry.
James Pryor II, Vice President with American Safety and Health Management Consultants Inc. (Ash,Inc.) has reviewed the latest available OSHA citations information and compiled this list of the Top 10 Most Cited Training Violations for the precision machining industry.
This listing also includes the OSHAweb link to information regarding each area , and training frequency and record retention information.
This is an example of a “Tool You Can Use” from PMPA to help you keep your shop compliant, competitive, and citation free.
Citation photo
While this application is medical, not metallurgical, the technology is worth a few seconds of your time…
Being a techie, I am always delighted by new technologies. So imagine when I found out about a $1.50 lensless microscope being demonstrated at Caltech.
As we implement new technologies in our shops we eliminate waste and become both more capable and more efficient.
This Caltech developed microfluidic microscope promises to improve efficiency, capability, and improve medical diagnostics in the third world where cost of detection is often a showstopper.
How do we currently diagnose diseases like malaria or cancer? A skilled technician examines blood samples brought to the lab using a conventional optical microscope.
Laboratory, sample preservation, preparation, and transportation all add “loss” to the process.
With this Caltech device, a system of microscopic channels called microfluidics lead a sample across the light-sensing chip. Samples flow through the channel because of a tiny difference in pressure from one end of the chip to the other. The chip ‘snaps’ images in rapid succession as the sample passes across.
Cells tend to roll end over end as they pass through a microfluidic channel allowing the device create an image of the cell from every angle. This allows the technician to determine its volume and type by viewing the video made by the device. No lenses, no slides, no expensive transportation or sample prep, just in situ testing.
So what do we call this approach? How about ” Subpixel Resolving Opto-Fluidic Microscopy” or “SROFM.”
This $1.50 lendless laboratory, when coupled with the growing ubiquity of cellular phones around the world, could just make a difference in developing world medical diagnostics and outcomes. REAL quality of life benefits from technology.
Full story at MIT Technology Review
We can see this type of application being developed for microtaggants on critical precision machined components for aerospace, medical or security applications where provenance and identity of the component are crucial to the mission…
Pure iron is barely harder and stronger than copper. Impurities are to iron, what paint is to an artist’s canvas.
- Red Ochre is Iron
The problem with iron at this level of purity is that it is too soft and too ductile for most commercial uses.
This means that the iron products that we know and recognize are relatively and deliberately impure.
Iron also has three allotropes or crystal forms, delta iron (body centered cubic) gamma (face centered cubic) and alpha, body centered cubic. I was originally taught* that delta and alpha iron were the same allottrope, a distinction that now appears to be a chrming sign of old age… and the addition of impurities (alloying elements) have different solubilities based on these forms.
It is the addition of carbon and other elemental impurities which alter these allotropic forms that gives commercial iron and steel products their diverse properties.
When we look on the material certs that accompany our steel products , the first element that is reported is carbon. Carbon is ubiquitous, and has the dominant effect on the behavior of the iron based product to which it is part, even in the presence of large amounts of alloying elements.
What is implied by the certs is that after adding up all of the elements reported, the balance of the material is “iron.”
In 2009 world Iron and steel production was estimated to be 1,219.7 million metric tonnes.
Physics trivia: Iron is the heaviest atom that can be made by the fusion of stars. Iron is is the ‘ash’ of stellar nuclear fusion. Iron is abundant- the fifth most abundant element on earth, and sixth most abundant in the universe. Our blood is red because of iron, and since iron is an essential part of our bodies, we can truly claim that we are “Stardust.”
Iron is essential to almost all living things indeed it is key to the working of hemoglobin and oxygen transfer in humans, as well as in enzymes that are involved in the creation of DNA.
Our bodies store surplus iron in the liver, to cover for those days when we do not get our required 7 to 11 milligrams of daily iron.
When properly contaminated with carbon, manganese, a sprinkle of sulfur or phosphorous, iron makes some damn fine precision machined parts too!
*I was originally taught= Alloying Elements in Steel by Edgar C Bain and Harold W Paxton, 2nd edition:
“The metal iron, as shown in figure 1., exists in two isometric allotropic crystal forms: (1) alpha and delta iron, whose solid solutions are called ferrite (or delta ferrite) and (2) gamma iron whose solid solution is is austenite.”
Cave painting
Poster
Lyrics by Jodi Mitchell, performed by Crosby, Stills, and Nash.
As a Lab supervisor in a Metalurgical Lab, quality pictures through the microscope was all in a days work.
Obtaining an appropriate sample.
Sample prep.
Using the tools at hand to create an appropriate image.
It was easy to desire better tools, more powerful microscopes etc.
But the proof of the image was more about our mastery of our tools and craft than it was about equipment.
As you will see on the Nikon Small World Competition site, these photos are “out of this world” and go far beyond what would be considered routine.
These folks have mastered their tools.
I am waiting for a high res photo of #18 by Gerd Guenther of Dusseldorf to add to this post. Believe it or not his image is of soap film-LIKE WE USE TO CLEAN OUR HANDS- OR WASH OUR PARTS.
Enjoy the images. Its a different world under the microscope.
Be amazed at the elegant complexity and order revealed at the smallest levels visible to us with light.
Enjoy!
A number of customers of the precision machining industry have started telling their suppliers (Us!) that we need to adopt SMED (Single Minute Exchange of Dies) Techniques so that we can reduce costs. We make it a rule never to prescribe solutions when we haven’t first diagnosed the problem…
Reducing setup time is important, but if that is not the constraint that is limiting your ability to serve your customer, why would you address that first?
The real issue that the customer has not brought to the table is lot size, economic order quantity (EOQ). Given an order quantity of 100 parts, if changeover time is 8 hours on a part with a one minute cycle time
- to make his parts originally takes 480 minutes of set up time.
- Plus 100 minutes (100 parts at one minute per part) to produce;
- Total 580 minutes or 5.8 minutes time per part.
The setup time is 480% of the actual process time to make the parts. 480/100= 480%
Reducing the set up to 4 hours set up, its now 240 minutes set up time plus 100 minutes to produce total 340 minutes or 3.4 minutes time per part. The setup time is now just 240% of the actual process (Cutting) time. The customer is saying that you should do this. And as far as you can, he is right.
But lets look at what the customer’s order quantity does to affect this.
Increasing just the lot size from 100 to 1000 pieces
- Results in the time per piece on the 8 hour setup being 480 minutes for set up plus 1000 minutes, or 1.480 minutes total time per part.
- The ratio of setup time to total time is now just 48%of the process time.
THATS A TEN FOLD REDUCTION!!! This is where the Bang for the BUCK is! If you could get your setup down to four hours, you’d be at 24% ratio of setup to total time.
On 10,000 pieces it becomes, at 8 hour set up, 480 minutes setup plus 10000 minutes process time; or about 1.048 total time per part; 4.8% is the ratio of set up to the process time.
WE CAN SEE that while reducing set up time is important and something that you can control, It is the increase in the lot size that is the most powerful determinant of the amortization of cost of setup. And your customer holds those reins.
ECONOMIC ORDER QUANTITY is in your customer’s control and ultimately delivers drives far greater savings than your cutting set up time in half, and in half again as we have just shown.
What he wants to ignore is that you have to set up the machine regardless of his lot size and he has to pay for it. So he wants you to reduce that set up as much as possible. However, there is no free lunch, there is always a law of diminishing returns, and he has to give you an order quantity that makes it profitable for you to set up your machine and produce the number of parts required.
Reducing setup time is important, but if that is not the constraint that is limiting your ability to serve your customer, why would you address that first?
Just cause that medicine sounds good to you Mr. Customer, doesn’t mean that it is the magic cure for everything. Increasing your Order Quantity may actually drive substantially larger savings.
Sometimes, more is better.
Medicine Photo
3-ON is the newest buzz word.
I’m starting to hear and see it more and more, like 24/7 was just a couple of years ago.
3-ON rhymes with Freon. but it talks about your company, your team, your own capabilityto get results:
ON Time.
ON Specification.
ON Budget.
3-ON. Its what ‘s expected.
Are you 3-ON?
Photocredits:
Time
Specification
Budget
Right on!
The China Price isn’t necessarily the Bargain that some buyers think it is…
- Reduce pipeline and surge inventory impacts on JIT operations;
- Improve the quality and consistency of inputs;
- Cluster manufacturing near R&D facilities, enhancing innovation;
- Reduce IP and regulatory compliance risk;
- And, most importantly to reduce Total Cost of Ownership (TCO).
This Total Cost of Ownership issue is the most compelling. It’s just the facts. The MATH is transparent.
You can get access to a host of reshoring information, including the Total Cost of Ownership calculator, by signing up at ReshoreNow.
The total cost of ownership calculator is an actual XL worksheet that will allow you or your customer to estimate the Total Cost of Ownership for a product that takes into account all of thecost factors that most people ‘gloss over’ in order to make their decision.
The concerns that we had about our work going to China remain a great introduction to the talking points of reshoring: here’s a Link.
Thank you Harry Moser for engaging your passion and experience on this critical to North American Manufacturing Issue.
The PMPA Business Trends Index showed a surprisingly strong August.
PMPA’s Index of Sales of Precision Machined Products in August 2010 climbed to 108, a surprisingly strong showing. The 8 percent increase in industry sales helped August to tie with June for the Sales Index High of the year to date, and since May 2009. August is the 6th month of what we have termed the new normal of sales at the Year 2000 baseline. August 2010 is up 34 points over August 2009. Two thirds of our respondents reported single or double digit gains in sales in August.
Members can download the full report here.
The Witch is dead!
The National Bureau of Economic Research issued a statement that the “trough” ended in June 2009.
So how come we feel like the house fell on us?
- Inavailability of skilled machinists
- China continues to manipulate its currency;
- North American OEMS continue to try to move work to China;
- Inavailability of credit from Banks;
PMPA’s Business Trends Sales Index proclaimed “The Lost Decade” in March and “A New Normal” in April.
The Lost Decade was when our sales index returned to year 2000 levels. The New Normal is its new range at those year 2000 levels.
See our announcement here.