Quench cracks result from stresses produced during the transition from Austenite to Martensite, which involves an increase in volume.
The martensitic transformation starts at the outermost surfaces of the part being quenched. As the transformation goes deeper into the softer austenite towards center of mass, its change in volume is restricted by the martensite already created in the outer volumes of the part adjacent to the surface.
This creates internal stresses which place the surface into tension.
When enough martensite has formed to create internal stress greater than the ultimate strength (tensile strength) of the as quenched martensite at the surface, a crack results.
As-quenched Martensite is hard and brittle- it has virtually no ductility.
Here are 3 ways to recognize a quench crack:
1) The crack runs from the surface towards the center of mass in a fairly straight line. The crack will also tend to be open or spread at the OD surface.
2) Quench cracks do not have decarburization apparent, since the quenching occurs at relatively low temperatures. If there is decarb associated with a crack, that shows that the crack existed at the time the material was at temperatures hot enough to decarburize. In other words, the crack existed prior to austenitizing.
3) The fracture surfaces will exhibit a fine crystalline structure. I remember the first time I saw a quench crack, thinking, “it crystallized.” Well, the steel is already crystalline, but the fine martensitic structure revealed by the crack showed that there was absolutely no ductility in the material…
Bonus tip: if you see a build up of scale in the crack itself, that tells you that the crack was there after quenching but before tempering. During the tempering operation at tempering temperature, oxygen in the atmosphere created a scale where it could reach the iron in the crack.
For more information on Quench Cracks, look at our blog posts Here and Here.
Author: Miles Free
Auto sales in the U.S. soared to levels not seen since the financial crisis.
This is great news for the precision machining industry, as Automotive is the single largest market served by our industry.
U.S. buyers bought some 1.5 million cars in August, resulting in a 17% increase over sales figures one year ago.
Moreover, the sales were spread across most manufacturers –domestic, new domestic, and foreign- and include increases in light trucks, compact cars and, electric vehicles.
The seasonally adjusted production rate for August pushed beyond 16 million units and some analysts believe that rate will be held throughout the remainder of 2013.
While not current, the graph above tempers this good news with a comparison of how far the market still has to grow to pre recession levels.
Flying car photo courtesy Popular Mechanics Story Top 10 Attempts to Build a Flying Car
Compiled from press reports.
Part Time Employment in a low paying field does not have to be your destiny. Mortgaging your future to enormous student loan debt that may or may not assure you a job capable of paying off the loans does not have to be your destiny either. Getting skills at a local community college can help you by pass the low paying part time underemployment that most Americans face today.
Last week we wrote about the growing spectre of part time employment displacing full time positions.
Today, University of Maryland Professor Peter Morici says “These days, new college graduates often work at unpaid internships while taking part-time jobs at places like Starbucks to meet minimal living expenses.”
“Since January, 936,000 additional Americans report working part-time, while only 27,000 more say they have obtained full time positions. The shift to part-time workers, partially a reaction to Obama Care health insurance mandates, puts downward pressure on wages and benefits in low paying industries, like retailing and restaurants, and widens income inequality.”
Morici’s point is that this is not a temporary problem- Expectations of permanently slower growth are hardening disturbing changes in the structure of the labor market and social conditions.
Manufacturing provides a respite from these problems for people with skills.
Our PMPA Business Trends Report shows half of our member company respondents scheduling overtime.
Regularly scheduled overtime is a far cry from part time underemployment.
The Economics and Statistics Division of the Department of Commerce just published a report Earnings of New Hires In Manufacturing.
- New hires in manufacturing enjoy an earnings premium relative to other new hires. This premium peaked during the recession but has returned to near its pre-recession average. At the end of 2011, the manufacturing earnings premium for new hires stood at about 38 percent.
- At the end of 2011, the ratio of new hire earnings to incumbent earnings was about 8 percentage points higher in manufacturing than in other industries.
- Over time, the earnings of new hires relative to incumbents have been consistently higher in manufacturing. From 2000 to 2011, the earnings of new hires were about 70 percent of incumbents’ earnings in manufacturing, compared to an average of 60 percent in other industries.
- Since the recession began, real average earnings for new hires in manufacturing grew 3.5 percent, while earnings of incumbents in manufacturing grew about 2.4 percent. Over the same time, real earnings for hires in other industries were flat, and earnings for incumbents in other industries declined.
Part Time Employment in a low paying field does not have to be your destiny. Mortgaging your future to enormous student loan debt that may or may not assure you a job capable of paying off the loans does not have to be your destiny either.
Getting skills at a local community college can help you find a fulltime position in advanced manufacturing where you can grow a career and get employer assistance with tuition and continue your education.
Who wants one size fits thinking all when it results in debt and underemployment for most?
For every full time job created in the United States in 2013, we have created 4 part time jobs.
If we were recovering, we would be creating more fulltime positions and fewer part time ones.
According to Forbes: “Bureau of Labor Statistics data show that the ratio of part-time to full-time jobs has completely flipped this year from historical trends. Last year, six full-time jobs were created for every one part time job. This year, only one full-time job is being created for every four new part-time jobs.”
On Aug. 2, the BLS reported nearly 90 million Americans were not currently in the labor force in July, with the percentage of the civilian non-institutional population not in the labor force now registering 36 percent.
The U-6 unemployment rate is 14%; the real unemployment rate- including those whop have given up looking for work is some number above 20%.
Advanced manufacturing, on the other hand offers skilled employees greater than full time employment.
Because of the shortage of skilled employees, half of our responding companies in our monthly Business Trends Survey are scheduling overtime. July Business Trends
So why no big speeches or parades or media events celebrating Labor Day this year?
Its because of the dire employment situation, silly!
U.S. Department of Commerce Economics and Statistics Administration just released a new report that describes why manufacturing jobs are good jobs using compelling facts and data from the Quarterly Workforce Indicators report.
New hires in the manufacturing sector fare better than new hires in other industries.
- New hires in manufacturing enjoy an earnings premium relative to other new hires. This premium peaked during the recession but has returned to near its pre-recession average. At the end of 2011, the manufacturing earnings premium for new hires stood at about 38 percent.
- At the end of 2011, the ratio of new hire earnings to incumbent earnings was about 8 percentage points higher in manufacturing than in other industries.
- Over time, the earnings of new hires relative to incumbents have been consistently higher in manufacturing. From 2000 to 2011, the earnings of new hires were about 70 percent of incumbents’ earnings in manufacturing, compared to an average of 60 percent in other industries.
- Since the recession began, real average earnings for new hires in manufacturing grew 3.5 percent, while earnings of incumbents in manufacturing grew about 2.4 percent. Over the same time, real earnings for hires in other industries were flat, and earnings for incumbents in other industries declined.
We have reported before about the difficulties of recent college grads to find meaningful employment, and that trend is widely reported in the press.
So imagine our delight to see authoritative statistics from the Dept. Of Commerce, with data from the Quarterly Workforce Indicators report, cross checked and validated against the Current Population Survey, that confirm that manufacturing new hires consistently earn a premium over others in other industries!
How big a deal is the earnings premium?
Figure 1 illustrates the earnings premium, that is, the average percentage earnings gap enjoyed by new hires in manufacturing compared to new hires in other industries. Prior to the recession, earnings of new hires in manufacturing were about 37 percent higher than new hire earnings in other industries. The premium for new hires in manufacturing began to increase in 2008, peaking at just over 50 percent in 2010. The premium has declined during the recovery but remains above its pre-recession level.
Looking for a career? Looking for Earnings?
The opportunities in manufacturing are convincing.
About a career in Precision Machining.
Earnings of New Hires In Manufacturing report from Dept. of Commerce
The Indiana/ Southern Ohio CPMPA Chapter is hosting a meeting and family social at Dallara Factory Tour on Friday, September 27, 2013.
The meeting will be held at the Dallara Indy Car Factory, 1201 Main Street, Speedway, IN. beginning at 1:00 p.m.
At 1:30p.m. a session on education programming for 2014 will be held, followed by a factory tour, race car rides and reception.
Focus for our attendees will be to tour the Indy Car Factory to get a behind the scenes look at the manufacturing process of a real Dallara Indy Car.
Of course other activities will make this a fun as well as educational event for attendees, including:
- Street Legal Racecar Rides offer an opportunity to ride in a racecar and capture the experience with a photo.
- No visit is complete without a Green Screen Photo with an Indy Car, putting you on the Yard of Bricks at the Indy Motor Speedway!
For more details and sign up about the PMPA meeting click LINK.
For more information about Dallara click here.
Chapter programming such as this Indy Car Experience Social is one more way that PMPA provides opportunities for members to network and learn.
The 2011 Reduction Drinking Water Act reduces the permissible Lead content in plumbing fixtures, fittings and components with wetted surfaces to a maximum of “not more than a weighted average of 0.25% (lead) when used with respect to the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures.”
This law goes into effect nationwide on January 4, 2014. It is in addition to other state regulations already in effect, including California AB 1953, Vermont’s Lead in Consumer Products Law, Act 193, and Maryland’s House Bill 372.
Certification by an independent third party that the products comply with the lead content limits are a requirement of the federal and some of these state laws.
ANSi/NSF 372 contains the lead content evaluation procedure originally detailed in ANSI/NSF 61 Annex G as well as testing and material lead content analysis. This standard applies ” to any drinking water system component that conveys or dispenses water for human consumption through drinking or cooking.” It matches the scope called for in AB1953 as well as the new federal rule.
The version available at the link above clarifies intent with regard to percent of threads regarding wetted contact area…
What are the implications regarding the upcoming January deadline for the Reduction of Lead in Drinking Water Act?
- You may be getting more orders for leaded products right now in an effort to beat the deadline
- You will not be able to manufacture components for ‘wetted application” from traditional High Lead materials after the law goes into effect in January.
- You will need to use less machinable (lower lead) materials for order that you receive going forward.
- Your shop throughput, efficiency, and capacity will be reduced by the move to less machinable materials.
Make sure that your sales people, estimators, and shop planners are up to speed on the consequences of this change to ‘unleaded.’
Our article “Adjusting to Unleaded” will help you understand this issue and its implications for your shop.
Our thanks to Chris Johnston Photography for the photo.
First you have to recognize it.
It is difficult to intelligently manage risk if you don’t even know how to measure that risk. What are the units?
The media talks today about “tapering” as if it is going to be news. Yet they fail to report the actual reality of the market consequences of the Fed’s Asset purchases.
First, a graph of the Fed Balance Sheet:
One result of this is a Volatility beyond our awareness.
Last week, the yield on the 10-year Treasury hit 2.855%.
On April 26, the yield was 1.64%.
That is an astounding 74% increase. In Treasury yields.
Pause.
For perspective, if the Dow had gained as much over the same time frame- it would now be in the 25,551 neighborhood!
The media is missing the story.
We have unprecedented volatility in our financial system today.
So how do we see it as manufacturers?
“The Commerce Department said on Monday (July) durable goods orders dropped 7.3 percent as demand for goods ranging from aircraft to computers and defense equipment fell. That was the biggest decline since last August and snapped three consecutive months of gains.”- Reuters
Contrast that to the gushing ISM report for July from the Economic Populist blog: “The July ISM Manufacturing Survey shows PMI had a blow out increase of 4.5 percentage points to 55.4%. Manufacturing has moved into sold growth with new orders increasing by 6.4 percentage points and production roaring in an 11.6 percentage point gain. Even the employment index increased.”
These are Volatile, Uncertain, Complex and Ambiguous times. We need to look for the story behind the story behind the story.
I am reminded of a classic Richard Pryor/Groucho Marx line “Are you gonna believe me or your lyin’ eyes!?”
When it comes to economic indicators, It is in our best interest to try to recognize and challenge the underlying assumptions.
How do you intelligently manage risk in the current economy?
Every one has a To Do List. Calibrate the gages, do the safety Audit, check the grinders , prepare for performance reviews. But what about a “To Don’t List?”
I was having a great conversation with a PMPA member about the need for editing in our shops- whose job is it to decide it is time to fire (edit) unprofitable customers? for example- when they mentioned in passing that something was on their To Don’t list.
I was on that new idea like a guy in the bleachers on hot dogs on $1 hot dog night.
We all maintain lists- To Do Lists- on scraps of paper, special forms, our cell phones and tablets, on apps… Yes, there is an app for that… including one aptly called, Anxiety
But who among us maintains a list of what we should not be doing?
Do you have a To Don’t List? What is on it that you can share?
Oh, and if you have a minute, check out the To Don’t List Blog
A lot of information is available stating that a college education is a great investment. The writers back their statements with data and statistics too.
What many fail to say, however, is the “Your results may vary” disclaimer.
If you can land a degree-relevant job, their data and statistics are correct.
But if you cannot land a degree-relevant job, the amount you are wagering on college is your
- actual out of pocket PLUS
- proceeds from college loans PLUS
- interest that you will have to pay until the loans are paid off.
All the while “NOT” getting a payoff for the “investment.”
So what are the chances of failing to land that degree-relevant job?
The good news is that underemployment among young college grads is now only 44% according to The Atlantic.
That is good news because last year the figure was over 53% were jobless or underemployed.
Sounds like more than a bit of luck is part of the college degree pathway.
The odds of landing a degree relevant job aren’t terribly encouraging while the debt and investment consequences are substantial- regardless of employment outcome.
What of those who do not find degree relevant employment?
According to the BLS Table 6: “15.1% of all persons with bachelor degree or higher that work at hourly wage rates are being paid at or below minimum wage.”
Here’s the table
Starting a career in precision machining does not require a substantial input of luck.
Within a year of skills training at a local community college you can have the skills needed to land a well paying job as a precision machinist. Our shops are hiring, sentiment for employment among our business trends respondents remains above 90%, and on average our shops are scheduling almost 3 hours of overtime. Each week.
A career in advanced manufacturing as a skilled precision machinist doesn’t take luck.
Thought you might like to know…