Author: Joe Jackson
Published July 17, 2023
Published July 12, 2023
Published July 10, 2023
Published July 1, 2023
Turned and polished steel bars have the mechanical properties of hot-rolled steel bars, but exhibit a greatly improved surface finish and dimensional accuracy. Turned and polished steel bars are produced from hot- rolled steel bars that have been descaled, straightened and had stock removal taken in a turning machine before final polishing. This minimizes any surface imperfections and ensures dimensional conformance with ASTM A 108 Table A1.1 (carbon grades) and Table A1.2 (alloy grades.) These bars are held to the same requirements for straightness (Table A1.4) as cold drawn. Turned and polished bars are relatively free from residual stresses, compared to cold-drawn, non-stress-relieved steel bars, due to the lack of cold-working strain.
The stock removal is taken from the outside diameter of the bar by tools held in rotating cutting heads as the bar is fed through the machine. A second station presses hardened steel rolls against the newly turned surface to smooth the surface and impart a bright finish. Turned and polished steel bars cost more than hot-rolled steel bars because of the cost of their processing as well as the yield loss resulting from the stock removal (chips removed) from the turning operation.
The turning and polishing process results in a bright finish relatively free of seams, slivers and other imperfections, but does not enhance mechanical properties because there is no cold work applied. The turned and polished bars are then protected with a rust preventive prior to packaging and labeling for shipment.
In contrast, to produce cold-drawn steel bars, hot-rolled steel bars, either in cut lengths or in coils, are first cleaned by shot blasting or acid pickling to remove the hard abrasive oxide scale on the surface.
Then they are pulled through a carbide die in the presence of high-pressure lubricants which reduces the bar’s cross section. This process is called cold work (no heat is added in the process).
The cold work trues up shape and holds diameter size to a very tight tolerance. The process also improves strength (increasing both yield and tensile strength) and hardness, while reducing ductility (% elongation and % reduction in area). The drawn bar is then straightened and cut to length with further testing for surface imperfections, if specified.
Bars then have rust preventive applied and are packaged and labeled for shipment.
The difference between turned and polished and cold- drawn steel bars is two-fold: (1) there is no cold-working enhancement of mechanical properties in turned and polished steel bars which means no improvement in machinability, and (2) turned and polished steel bars have had stock removal taken to minimize surface imperfections, cold-drawn steel bars have had no stock removal taken.
Why Choose Turned and Polished Bars?
The turning operation adds value by improving the quality of the hot rolled, as rolled steel bars, by minimizing decarburization, seams, slivers and any other surface imperfections. As no cold work is performed, the mechanical properties of the turned and polished bars are those of the hot-rolled steel bars used as their feedstock.
The process of cold drawing is done at ambient temperatures, increasing mechanical properties by a process called cold work. This cold work increases yield strength, substantially; the tensile strength somewhat; as well as the hardness. At the same time, the ductility is reduced. These changes improve the steel’s machinability.
Turned and polished bars are therefore a less suitable choice for machining, as the lack of cold work makes them less machinable than a comparable cold-drawn bar. Turned and polished bars are used in applications requiring a minimum of machining such as shafting and power take off applications where little machining to produce the part are required.
Tolerances for both turned and polished and cold- drawn steel bars are unilateral (to the minus only) from the specified size. Out of roundness in these products is one-half the size tolerance, per footnote D for both tables. The chemistry which identifies the material as a particular grade as well as other requirements such as product analysis tolerances and grain size can be found in ASTM A 29, Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot Wrought, which is included by reference in ASTM A 108.
The reasons to select a turned and polished steel bar are few but compelling:
What don’t you get with Turned and Polished Steel Bars?
Enhanced mechanical properties. And, because of that, lower machinability. As no cold work has been imparted to the material, the existing mechanical properties of the starting hot-rolled steel bar carry over into the turned and polished bar. This results in lower machinability than found in a cold-drawn bar. What you do get is similar dimensional and straightness tolerance, bright smooth finish, relative freedom from decarburization, seams, slivers and other surface imperfections. Turned and polished bars are often the choice for safe reliable transmission of torque and mechanical power. For applications where resistance to wear is required, turned and polished bars can have their surface enhanced by hardening treatment.
Final Word — “Cold Finished” Steel Bars
Both turned and polished and cold-drawn steel bars are “cold-finished” steel bars. They are processed at ambient temperatures. So, when someone uses the term “cold-finished steel bar” it is important to determine exactly what they mean by cold finished. For best machinability — and enhanced mechanical properties — cold drawing is indicated. Turned and polished is often the best choice for shafting and other applications requiring little machining but having a high need for surface and dimensional integrity.
Miles Free III is the PMPA Director of Industry Affairs with over 50 years of experience in the areas of manufacturing, quality and steelmaking. Miles’ podcast is at pmpa.org/podcast. Email Miles
Published July 1, 2023
Marketers are responsible for the corporate brand, public relations, marketing campaigns and all the channels and events it takes to get the message to the customer. Debra Beevers is the marketing director for Concast Metal Products Co.in Wakeman, Ohio. Courtney Ortner is the director of marketing for the A+ Automation Team at Absolute Machine Tools in Lorain, Ohio. Both women share their journey to manufacturing.
Debra Beevers’ Journey
Debra started her business career at a local hospital and also in real estate. When she entered manufacturing in 1989, she didn’t have any industry experience. After 20 years in metals, she started with Concast Metals in 2009. Concast is a company that encourages engagement, continuous improvement, product development and customer service. Debra has found this company culture makes her job very enjoyable and rewarding. She also values new experiences and acquiring new skills, and is known for saying, “you add new tools to your tool belt with every experience.”
Courtney Ortner’s Journey
Courtney worked in sales and marketing for Procter & Gamble. She turned down an offer to relocate to stay with her then-fiancee, Steve Ortner, owner of Absolute Machine Tools and, 31 years later, she is still at Absolute. She served as the director of marketing for the CNC side, but later realized the future demands for cobots and formed the A+ Automation Team. She is proud of creating the team and says she feels like a superhero when they help manufacturers solve employment and throughput issues.
Advice to Women (or Anyone) Seeking a Career in Manufacturing
According to Debra, “It has been a great experience working in this industry. When I started 34 years ago, I was often the only woman in the room within an industry heavily dominated by men. That trend has changed through the years. Women have a lot to offer and their contributions to the manufacturing industry are being recognized and rewarded. Energized by these facts and understanding how important networking can be to their careers, I highly encourage women at all levels to get involved in PMPA and other organizations like CBSCA and AWMI.”
Courtney encourages women to “Go for it, ladies! Manufacturing any product not only takes skills but also thorough and smart thinking. Women are creative and excellent thinkers, organizers, planners and possess a natural drive to get things done. American manufacturing needs people like this, and so women are already prequalified to be successful in the manufacturing industry.”
Carli Kistler-Miller, MBA has over 25 years of experience with
communications, event/meeting planning, marketing, writing and
operations. Email: gro.apmp@rellimc — Website: pmpa.org.
Published July 1, 2023
Fabricated Metal Products Manufacturing is a subsector of manufacturing that makes critical goods from metal components.
Precision Turned Products Manufacturing is a subsector of fabricated metal product manufacturing that makes the components that MAKE IT WORK!
INDIANA ECONOMIC OUTPUT
Indiana Manufacturing
NAICS 31-33
$104,750,000,000
Fabricated Metal Product Manufacturing
NAICS 332
$16,175,389,000
Precision Turned Product Manufacturing
NACIS 332721
$771,671,000
INDIANA MANUFACTURING ACCOUNTS FOR
Manufacturing Is Productivity – 26.56% of the Indiana total output (GDP)
Manufacturing Builds Businesses – 6,942 manufacturing establishments are in the state of Indiana.
Manufacturing Creates Jobs – Jobs: 17.51% of all Indiana employees are in the manufacturing sector. (546,000 employees)
Manufacturing Earns Export Dollars – Jobs: 17.51% of all Indiana employees are in the manufacturing sector. (546,000 employees)
Manufacturing Drives Economies – Indiana’s output generated by its manufacturing sector is worth more than $150 billion a year to Indiana’s economy.
Manufacturing produces for INDIANA!
Indiana is a great place for a career in manufacturing
Published July 1, 2023
By David Wynn, Technical Services Manager, PMPA
How many times have you tried to get a screw out of a holder only to have it so tight that you break the screw getting it out? You have followed the torque specs. Everything was done right, but after 40 hours of run time that screw just won’t come out. This is something I have fought for years in the shop.
This was a tip provided to me by PMPA’sJoe Gentile. I had a member shop put it into practice to see if there was a difference and they have seen a major improvement in screws not seizing in holders. Putting a little anti-seize on every screw when you change inserts has nearly fixed this problem. After a test of 100 insert changes here are the results.
You need to dab a little on the start of the thread. Take the screw and run it up between your fingers while screwing the screw between your index finger and thumb. This works the anti-seize down into the threads with a smooth consistency. You don’t want to overdo it. Having too much invites dirt, debris and chips to stick to the threads. A little goes a long way. Why do we need to use anti-seize? What causes this problem to begin with? It comes down to three main factors.
Friction. Debris get into threads no matter how much we clean them — microparticles in unfiltered coolant. Vibration works small particles down in there which increases the friction to remove the screw. Anti-Seize helps seal the thread from debris and provide additional lubricity, decreasing friction on removal.
Corrosion. Corrosion is a problem everywhere, but even worse on machines using water-based coolants. The threads build up with corrosion causing them to stick together, dramatically increasing the force required to remove them. Also, corrosion weakens the structure of the thread. Making them more prone to breakage. The sealing provided by anti-seize as well as the anti-corrosive properties help protect the threads from corrosion.
Galling. Galling is generally a product of over torquing, but can come about from vibration. Galling also is known as cold welding. The thread is pressed together so tightly that it literally forms a bond. In extreme scenarios, there can be so much pressure and heat that the fasteners literally weld together. Changing inserts by feel without torque wrenches is often the cause. Anti-seize creates a thin layer between the two surfaces, preventing galling.
Use of anti-seize in threads can reduce torque values required by 25-30%. The anti-seize forms a small layer between the threads, so you get a more consistent clamp across the whole body of the thread. I suggest putting some anti-seize in little magnetic spice containers and hanging them on every machine, so, it’s always right there to use. If you put it right by the machine door, it’s a visual management technique to remind our performers to dab a little anti-seize. A little dab will prevent the headache of a broken screw and a down machine.
David Wynn
David Wynn, MBA, is the PMPA Technical Services Manager with over 20 years of experience in the areas of manufacturing, quality, ownership, IT and economics. Email: gro.apmp@nnywd — Website: pmpa.org.
Published July 3, 2023
Published June 29, 2023
Published June 26, 2023