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?"
Our post on "No Gloves When Working on Grinders" has prompted a number of responses. Here are some additional reasons why you should not need gloves when working on grinders and grinding machines.
Issue: There are sharp edges or burrs that will cut me if I hold the part. The grinding will be to remove the burrs.
Response: Use a file to knock down the burrs so that you can safely hold the part for grinding, or use leather finger cots to grip the part for grinding.
Issue: The part gets too hot to hold.
Response: Then you are grinding wrong. Here is a list of some of the things that can go wrong by letting the heat of grinding get out of control:
Remove the temper from steel. Especially on tools, loss of temper means loss of tool hardness and edge life. A drop from Rc63 to about Rc48 for a couple of tenths (0.0002-0.0005) can contribute to side wear and edge failure.
Crazing or checking on carbide can be caused by burning during grinding.
Work hardening. Overly shiny surfaces are usually the clue that work hardening has occurred.
Creation of untempered martensite.
Untempered martensite can be formed in high carbon and alloy steels by getting high surface temperature from grinding—red heat—then quenching in water. Untempered martensite is very brittle and reduces toughness.
Keeping the work cool continuously while grinding is an important aspect of preventing damage to work, the wheel, and injury from occurring to the worker. Hogging off material and infrequently quenching is a great way to destroy a tool by grinding.
Water needs to be plentiful to absorb the heat from grinding, and frequently used to reduce heat buildup in the work.
Take multiple small passes and cool in between in a large bath of water while grinding to minimize heat buildup.
Wearing the required PPE, making sure the grinding wheel is properly dressed, all guards are in place and properly adjusted are also key to safe grinding in our shops.
Bottom line: If the work is too hot for your fingers, it may be approaching the danger zone regarding loss of mechanical properties and function in end use.
If there is a worse combination than grinders and gloves, I don’t know what it is, except perhaps gloves and a drill.
We posted a really cool video on our career blog about making a light saber sword here. But we were shocked to see the guys in the video wearing heavy leather gloves while working with grinders. By “grinders,” we mean abrasive belt grinders, bench grinders, pedestal grinders, surface grinders, and also abrasive cutoff machines.
Sanders, polishers and buffers that involve rotating wheels or transversing motion are also included in this classification for the purposes of hazard analysis.
Here are six reasons to not wear/not permit the wearing of gloves while working with grinders or grinding machines:
Withdrawing proposal for a Factoryless Goods Producer Classification in NAICS 2017.
In a resounding victory for actual manufacturers—the people that make things—the Office of Management and Business reported on August 8 that the proposal to create a “Factoryless Goods Producer” classification for the NAICS 2017 has been withdrawn.
PMPA has been on the forefront of challenging the classification, which would have created a class of phantom manufactures that did not actually manufacture goods, but rather purchased finished goods for resale, and possibly from foreign sources.
On May 22, the administration announced the U.S. Census Bureau was considering a proposal to count a business as a manufacturer, even if they outsource all of the transformation steps traditionally considered production activities, or manufacturing. The proposal would have counted some activities outsourced overseas as U.S. manufacturing and included financiers and others as manufacturers even though they never visit a shop floor.
Among PMPA’s objections to the scheme were the following:
NAICS is based on the primary activity of an establishment
NAICS is for classifying domestic activities only
If manufacturing processes are not actually required for a “manufacturing” classification, the statistics produced by such a distorted definition are virtually useless
“This is an important victory for U.S. businesses, and we applaud the administration for recognizing the flawed thinking behind this proposal,” says Mike Kobylka, executive director of PMPA. “This proposal would have created a class of phantom manufacturers. The NAICS classification system has never and should never take into account foreign sourced production processes.”
More than fools gold, iron pyrite can prevent steel from being hot worked by inducing "hot shortness."
Manganese ties up sulfur before it can chemically combine with iron to form iron pyrite. Iron pyrite occurs at grain boundaries and leads to hot shortness (brittle behavior) at rolling temperatures.
Several people found PMPAspeakingofprecision.com blog with the search term “Carbon Steel Without Manganese.” So we’ll take this opportunity to address this. We have already written “5 Facts about Manganese in Steel,” which explains the contributions of manganese to a steel’s properties. But let’s answer the question, “Is there a carbon steel without manganese?” The answer is no, and primary reason is because of iron pyrite.
There are always small amounts of sulfur in steel, and sulfur combines with the iron in the steel to form iron pyrite. Iron pyrite is also known as iron sulfide, though a more descriptive name might be iron persulfide.
Regardless, the iron pyrite material is formed as sulfur in the melt reacts with iron, segregates at grain boundaries and causes intergranular brittleness at rolling temperatures. This causes it to break, rather than behave in a ductile fashion and reduce under the pressure of the rolls.
By adding manganese to the melt, manganese preferentially ties up the available sulfur, forming manganese sulfides. This prevents the formation of iron pyrites in the grain boundaries, preserving the ductility of the steel at rolling temperatures. That is why every steel that we have encountered contains enough manganese to react with the sulfur in the melt.
Steel without manganese? I’ve never encountered it. And that is a good thing.
When these workers leave, we will need skills to replace them. What is your plan?
Openings for skilled workers as older workers retire are seen as the biggest challenge facing manufacturers in this economic policy report from Connexus Indiana and CBER Muncie.
“The most significant challenge facing Indiana’s manufacturing firms is the very high percentage of workers nearing retirement age (more than 1 in 6 workers over the next 10 years).”- CBER Manufacturing and Labor Market Frictions, Connexus Indiana, CBER Muncie Indiana.
“Since 1998, the share of manufacturing workers age 55 to 64 has grown from 9.8 percent to 16.8 percent, which is a 71-percent increase in share in less than a generation’s time. This rapid growth is because of the movement of the baby boom generation into near-retirement and retirement years. Although this transition is occurring across the economy, it is larger and growing more rapidly in manufacturing.”
And it is not just in Indiana. This trend can be seen nationwide. Skilled workforce: our greatest challenge.