Straight from the baker to you…
1) Inclusions are on the inside, not on the outside surface…
2) Inclusions are non metallic materials entrapped within a solid metal matrix.
3) Inclusions that are typically expected include Sulfides (Type A), Aluminates (Type B), Silicates (Type C) and Globular Oxides (Type D)
4) Other types of inclusions are called exogenous inclusions as they come from materials not expected to be entrained or entrapped within the steel- typically slag or refractory that might have broken off during steelmaking.
5) Inclusions are measured and rated in North America according to ASTM method E45
6) Bearing Quality Steels use a number of different practices in order to minimize the inclusion content (because inclusions would wear differently than the host metal, thus nucleating premature wear and failure.)
7) Steel Cleanliness, Steel Microcleanliness, and Inclusion content are all different ways of talking about the presence of these non metallic particles within the steel itself.
Three reasons inclusions are normally expected in plain carbon and alloy steel bar products in our shops:
‘8) Manganese sulfides are expected to be present as they aid machining.
9) Silicates are expected to be in non- free machining steels as silicon is added as a deoxidizer to assure the soundness (freedom from gas bubbles and voids) of the steel
10) Aluminates are also expected if the steel is ordered as Aluminum Fine Grain. the Aluminum scavenges Oxygen and nucleates the formation of fine grains of austenite.
11) The Manganese Sulfides promote free machining as they provide a place for the chip to break and help control welding of material (built up edge) on the tool edge. In leaded steels, the lead is closely associated with these manganese sulfide inclusions.
12) The Silicates and Aluminates in our common steel grades are of high hardness, abrasive, and are a primary reason for tool wear and edge chipping in ordinary steels.
13) A quick look at the certification tells us whether or not we will find these kinds of inclusions- just look at levels of Manganese, Sulfur, Silicon, and Aluminum.
For machining, in keeping with the baking theme, I like to think of Manganese Sulfide inclusions as “kinda like the raisins in raisin bread.”
Bakers dozen photo credit.
Author: Miles Free
This graph is pretty clear.
PMPA’s Index of Sales of Precision Machined Products in February 2011 was 110, staying even with the adjusted value for January 2011. (January had been reported at 111.) February’s index of 110 remains at its highest level in the thirty-two months since June 2008. Additional data in the February report indicated the industry is recovering nicely, and outlook is positive. The February 2011 sales level was equal to the February 2008 level prior to the Economic Recession.
This strong showing of industry sales is a clear signal that we need to adjust from our recessionary mode “hunker down” management style to a recovery mode “aggressively manage risk” methodology if we are to take full advantage of the markets today.
More than ever before, the keys to our company’s success are in our hands, not market externalitites.
PMPA members can read the full report at this link.
Accredited Press please contact PMPA for a copy of the report.
While we were glued to our TV’s and monitors Monday looking at the destruction from the earthquake and tsunami that washed over Northeastern Japan, another economic tsunami went mostly unnoticed in the global press.
“China has become the world’s top manufacturing country by output, ending the US’s 110 year run as the largest goods producer,” wrote Peter Marsh in Monday’s Financial Times.
The change was noted in a study from IHS Global Insight, which estimated that lst year, China accounted for 19.8 % of world manufacturing output, just ahead of the US, which was reported as 19.4% in the page 4 story in the Financial Times.
The value of these outputs was $1.995 trillion for China, $1.952 for the US.
So whats the good news in this report for the US?
“The US has a huge productivity advantage in that it produced only slightly less than China’s manufacturing output in 2010 but with 11.5 million workers compared to 100 million employed in the same sector in China.” – Mark Killion, IHS Global Insight World Industry Services.
Also, we need to remember that much of that Chinese manufacturing output was produced by Chinese subsidiaries of US companies, and based on US derived technologies. Some consolation that is…
And a frustrating final footnote, part of the boost can also be attributed to the 3% appreciation of the Chinese Yuan to the US Dollar between 2009 and 2010. Be careful what you wish for…
1) Martensite is the hardest and most brittle microstructure obtainable in a given steel.
2) Martensite hardness of the steel is a function of the carbon content in that steel.
3) Martensite results from cooling from austenitic temperatures rapidly by pulling the heat out using a liquid quenchant before pearlite can form.
4) As quenched Martensitic structures are too brittle for economic use-they must be tempered.
5) Reheating as quenched Martensite to a temperature just below the AC1 results in the best combinations of strength and toughness.
Because Martensite transformation is almost instantaneous, the Martensite has the identical composition of the parent phase, unlike ferrite and pearlite which result from a slower chemical diffusion process, so each have different chemical compositions than the parent austenite.
Formation of Martensite involves a transformation from a body-centered cubic structure to body-centered tetragonal structure. The large increase in volume that results creates a highly stressed structure. This is why Martensite has a higher hardness than Austenite for the exact same chemistry…
Photo and Graphs Credit: Cold Finished Steel Bar Handbook
Recently PMPA member Darlene Miller told the White House Jobs Council that what we needed were skilled workers.
“Not just labor, we don’t have labor jobs, we need to hire people with skills. People who can add value right away when they start on the job.”
Here’s a video from NBC news last week that shows the same thing.
The want ads list plenty of openings for skilled set up personnel and machine operators.
Interestingly- they did so even through the worst of the recession.
Get skills to get a job.
On February 10th 2011 OSHA issued new enforcement guidelines in regards to personal protective equipment (PPE).
Here’s the link: PPE Enforcement Guidance
“This instruction, Enforcement Guidance for Personal Protective Equipment in General Industry, establishes OSHA’s general enforcement and guidance policy for its standards addressing personal protective equipment (PPE). It instructs OSHA enforcement personnel on both theagency’s interpretations of those standards and the procedures for enforcing them.”
The scope of this enforcement guidance includes head, face, eye, foot , respiratory protection , protective clothing and electrical protective equipment. All per 29 CFR 1910.132 through 29 CFR 1910.138. The areas that will directly impact Precision machining establishments include:
1) Assuring that the proper personal protective equipment has been properly chosen and issued,;
2) An active program of enforcement is in place on its proper usage.
3) Documentation should be in place in regards to both of these aspects, as well as regarding no cost to employees as discussed in the new guidance provision.
Have you reviewed your company’s personal protective equipment policy / program ?
Are you aware of the new OSHA enforcement guidance?
Below are a few tips to consider in your review
- Has a Job Safety Analysis been performed on all tasks to determine if PPE is required ?
- Has the proper PPE been selected?
- Is the PPE properly maintained, inspected and stored ?
- Have medical exams been given to employees in reference to the use of certain types of PPE?
- Are all records pertaining to your PPE program current ?
The new guidance document is a 54 page .pdf easily downloadable. I’d urge you to download and review it now.
Post coauthored by James Pryor and Miles Free
photo Copyright (C) 2003-2011 Miles Free
PMPASPEAKINGOFPRECISION.COM was listed in Orthoworld’s BONEZONE Spring 2011 Industry Watch column as a “Blog or App That Brings Solutions.”
BONEZONE is the premier journal for orthopaedic device company professionals at all levels of the supply chain. We follow Bonezone ourself to stay up to date on the orthopedic Industry’s latest challenges and opportunities, and its editorial coverage of product design and development, supply chain optimization, regulatory processes and insights into the state of industry and cutting edge technologies.
We were pleased to be recognized by this leading publication as a solution provider for shops that make orthopedic and medical implants. We focus on regulatory and material impact on shops like yours. They focus on challenges facing the broader orthopedic industry.
Yay team.
Bonezone Spring 2011 Speakingofprecision
Thermal effects can affect your results.
Its consistency of temperature, not the actual temperature, that is important.
Thermal errors can stack up.
For measurement uncertainty purposes, you want to assure that linear expansion dimensional errors attributable to temperature variation are minimized- less than 10% of your intended accuracy.
Thermal Expansion Coefficient – The thermal expansion coefficient (CTE) of tool steel is added to the measurement uncertainty calculation where relevant. The Testing Laboratory considers consistency in temperature most important. This policy was derived from MIL-STD-120 which states: “Whenever precision measurements are to be made, the temperature should constantly be kept as near to 68 degrees as possible. Since most gages and measuring instruments are usually made of steel…..the requirement that the temperature remain constant is more important than the actual temperature.”
Based on the above statement in bold, our laboratory tracked the temperature with its computerized temperature control system over a period of a month in order to determine the amount of deviation from 68 degrees. The amount of this deviation is used to calculate the Linear Expansion per unit length per degree Fahrenheit. This amount is used in the calculation of relevant measurement uncertainties.
For steel, the coefficient we used was 0.000006″ per degree of temperature change. (That’s six millionths of an inch per degree F)
For copper and copper alloys we used 0.000009″ per degree of temperature change. (That’s nine millionths of an inch per degree F.)
For aluminum, the figure we used was 0.000013 ” per degree of temperature change. (That’s thirteen millionths of an inch per degree F.)
While room airconditioning is important don’t forget that handling gages can affect your measurement system too.
Note that gaging can pick up operators body heat and that temperature errors can thus stack up…
http://www.commodorecomputerclub.com/images/020411/IMG_1868.jpg
Charles Martin Hall discovered the electrolytic process for extracting Aluminum from its oxide, 125 years ago from tomorrow. Hall later went on to co-found ALCOA, and gifted his Alma Mater, Oberlin College, with 1/3 of his estate.
Patent number 400664 was issued to him on 04. 02. 1889. See the patent here.
Paul T. Heroult made the same discovery around the same time, and history credits both men for this accomplishment by calling it the Hall-Heroult process.
Aluminum is a critical material of our modern technologies- airplanes, air conditioning and refrigeration parts, engine blocks, cookware, beverage cans. As copper prices continue to escalate, our customers are finding aluminum parts are becoming viable substitutions. And the price of aluminum seems less variable, too. Thats good news for shops that make parts out of aluminum.
According to the Metal Service Center Industry association:
U.S. aluminum shipments finished 2010 some 25.8 percent higher at 1.3 million tons and rose 7.7 percent in Canada, to 135,200 tons than 2009.
U.S. metal centers shipped 100,300 tons of aluminum products during December, or 26.7 percent more than during December 2009. Aluminum inventories at the end of the year totaled 347,900 tons, 33.5 percent above the stockpiles of a year ago and equal to a 3.5-month supply.
In Canada, service centers shipped 9,000 tons of aluminum during December, up 16.7 percent from the same month last year. Aluminum inventories at year end of 31,300 tons were 7.2 percent above stocks at the end of 2009 and equal to a 3.5-month supply.
Aluminum shipments indicate economic recovery is in process.
We believe that continued demand for copper in global developing economies will increasingly make aluminum a cost effective substitute. Add demand for lighter weight vehicles and improved fuel mileage and we can see that aluminum will continue to increase in its use in our shops.
And to protect our critical thinking…
Hall and Hall Cell
MSCI Link
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