PMPA Speaking of Precision Podcast:
Twist Drills for Success
Miles Free, Carli Kistler-Miller and David Wynn go through the criteria to consider when choosing a twist drill for machining precision parts.
Published June 19, 2023
Author: Joe Jackson
PMPA Speaking of Suppliers Podcasts:
How Culture is the Key of Precision Ground Stock
Miles Free discusses culture with Laurent Cros of Boston Centerless a Shigeo Shingo Award winning company. The discussions digs into how Boston Centerless uses BC vision to run their business. The importance of internal customers in manufacturing. Laurent ties culture back to quality in there BC system. A great discussion about culture, grinding, processes, and much more.
Published June 14, 2023
PMPA Speaking of Precision Podcast:
Is Practice Considered Continuous Improvement?
Does practice make perfect? Miles Free, Carli Kistler-Miller and David Wynn investigate if continuous improvement is discouraged by frozen practices, locked in processes, and rote practice.
Published June 12, 2023
PMPA Speaking of Precision Podcast:
Additive v. Subtractive Manufacturing
Miles Free, Carli Kistler-Miller and David Wynn dive into the great debate of additive versus subtractive manufacturing for our precision machining shops.
Published June 5, 2023
STATE OF MANUFACTURING – Texas Manufacturing
by Joe Jackson
Marketing & Events Assistant, PMPA
Published June 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!
TEXAS ECONOMIC OUTPUT
Texas Manufacturing
NAICS 31-33
$226,950,000,000
Fabricated Metal Product Manufacturing
NAICS 332
$28,576,899,000
Precision Turned Product Manufacturing
NACIS 332721
$767,429,000
TEXAS MANUFACTURING ACCOUNTS FOR
Manufacturing Is Productivity – 11.91% of Texas total output (GDP)
Manufacturing Builds Businesses –17,720 manufacturing establishments in the state of Texas.
Manufacturing Creates Jobs – Jobs: 6.86% of all Texas employees are in the manufacturing sector. (897,000 employees)
On average, each manufacturing job created provides 5 additional jobs in Texas.
Manufacturing produces for TEXAS!
- Texas manufacturing accounts for one-tenth of all manufacturing dollars generated in America.
- Manufacturing is the third largest GDP producer in Texas
- Fabricated metals is the second largest manufacturing sector in Texas.
- Manufacturing plays a significant role in Texas’s reign as the nation’s #1 exporting state for more than 20 years.
Texas is a great place for a career in manufacturing
- Manufacturing jobs pay on average 39% over the average job in Texas. (according to NAM.org)
Sources: NAM.org, US Census, Businessinsider.com, Industryselect.com, Manufacturetexas.org.
Data selected to show relative values. May not be directly comparable due to differences in sampling, analysis, or date obtained.
The Battle For Performance: Efficiency Versus Effectiveness
Does your daily activity have anything to do with your effectiveness? The answer may surprise you.
by David Wynn
Technical Services Manager, PMPA
Published June 1, 2023
There is a battle going on in your shop. You may not realize it, but it happens every day. It is the battle between efficiency vs effectiveness.
I know some of you are saying to yourselves “efficiency and effectiveness are the same thing, right?” Well, let’s define them and find out.
The American Dictionary defines, effectiveness as “the ability to be successful and produce the intended results.” According to Merriam-Webster.com, efficiency is defined as “what is capable of producing desired results without
wasting materials, time, or energy.” Now we can see the true difference. Efficiency is doing something using the least amount of time — producing the items with the least amount of inputs to achieve the output. Effectiveness is producing the intended, the desired result. We can produce parts at five seconds for hours but if they don’t hold tolerance, we are not being effective. We are efficient with our fast cycle time but not achieving effectiveness. Our customers only pay
for effectiveness. Effectiveness is our parts that meet dimensional tolerances in the box ready to go to the customer.
I think we get lost in our quest for lowest cycle times — which we think of as being efficient and sometimes miss the mark on effectiveness. We strive to get the fastest cycle time possible. What happens when our performers must stick their head in a machine every ten minutes to change an insert? Yes, it is running in 10 seconds, but it is down 50% of the time because of the increased down time for tool changes. What if we adjust our feeds and speeds a little, take it down to 15 seconds and the job runs all night? Yes, 15 seconds is technically 50% less efficient, but now we get 90% production and can run 10 hours unattended. Which machine has more parts produced by tomorrow morning? The machine with the performer tinkering every ten minutes, or the machine running all night?
We need to learn to be effective with our efficiency for the right things. This idea is very similar to Jim Collins Good To Great bus example. We must get the right people on the bus then make sure all the people are in the right seats on the bus to succeed. In our shop processes, we must do the right things. Then we must become very efficient at doing those things. The challenge is to start with yourself. At the end of every day for a week, sit down and make a list of everything you accomplished. At the end of the week, mark which activities you did that were effective. You may be surprised at how much activity you do every day has nothing to do with your effectiveness. After you see the waste in your personal effectiveness, start to look at the waste is in the shop. We want to do those things that matter. We want our performers working effectively at all times. Granted, 100% effectiveness is not achievable, but like a true North vision, it gives you direction.
To be effective is to have the most compliant parts in the bucket at the end of 24 hours. (Or to have completed the most meaningful work.) Effectiveness is the long-term view. Trying to accomplish tasks purely based on efficiency shifts
our focus from quality to time savings. This is a shortsighted approach to mistakenly maximize our here-and-now. But
our true goal for our organization is long-term success. To be truly effective is to be efficient in the right things. Are you
efficient in the right things? At the end of the day did you get the most parts in your bucket?
Author
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 David
Cold Drawn Steel Bar Stock: How it is Manufactured, Benefits to Your Shop
Understanding the benefits provided by cold drawn steel bar stock can help you optimize the work that you quote by maximizing benefits to your manufacturing process and customer
by Miles Free III
Director of Industry Affairs, PMPA
Published June 1, 2023
How Are Steel Bars Cold Drawn?
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. Further testing for surface imperfections if specified. Bars then have rust preventive applied and are packaged and labeled for shipment.
Why Cold Drawn Steel Bars?
The process of cold drawing, is done at ambient temperatures, transforms the material 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, which improves the steel’s machinability. Because the cold drawing work is done at ambient temperatures, the tolerance achieved for size and out of round is held to just a few thousandths of an inch. By convention, tolerances are held to the minus, nothing to the plus. This makes loading into workholding more
convenient and the material diameter and shape are often useable as is for many mechanical components.
Specifications for Cold Drawn Carbon and Alloy Steel Bars
Cold drawn carbon and alloy steel bars are specified in ASTM A 108 Steel Bar, Carbon and Alloy, Cold-Finished. Size tolerances for Level 1 Carbon Steel Cold-Finished Round Bars (Cold Drawn, or Turned and Polished) can be found in Table A1.1 of ASTM A108. For alloy grades, the size tolerances are found in Table A1.2. Tolerances are based on bar diameter, and carbon content and thermal treatment specified, if any. Tolerances are unilateral (to the minus only) from the specified size. Out-of-roundness in these products is 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 cold drawn steel bar are few but compelling:
• The hard abrasive scale has been removed — preserving tool life as well as metalworking fluid utility. The cold drawing operation improves the as received surface finish of the bar.
• The cold working strain imparted by cold drawing improves the machinability of the material (not only the ease of removal of chip but also the resulting surface finish.)
• The tight dimensional and out of round tolerance may result in a reduction in processing needed.
• The straightness (lack of runout) as well as the better concentricity and dimensional tolerance allows for higher rpms. The higher surface feet per minute, increases output.
• The higher mechanical properties mean that the part may withstand higher stresses and forces in the customer’s application. This makes cold drawn steel bars ideal for shafting and power transmission applications.
• Standard grades are widely stocked and available for prompt delivery.
While the cold drawn bar as shipped has a bright, smooth, workmanlike surface, since no stock removal was taken, it is not warranted for surface finish. However, the bright drawn finish is often suitable without any additional processing. Typically, surface finish is in the neighborhood of 125- 32 microinches using normal processes. (Machinery’s Handbook) However, many of today’s mills have specialized processes that can deliver better.
What don’t you get with cold drawing?
As no stock removal has been taken, there is still the possibility of seams and other surface imperfections. This possibility increases when the steel is resulfurized. While the sulfur promotes better machining, it also increases the possibility of seams and other surface imperfections. ASTM A 108 table A1.8 provides the surface discontinuity
tolerances for carbon and alloy bars, based on sulfur content and bar diameter.
Material may be in stock available for prompt delivery.
Finally, a less important but often overlooked factor is that cold drawn steel bars are the most widely used feedstock in most of our precision machining shops. As a standard raw material, produced to standards for chemistry and tolerances, our shops are able to gain experience and understand what to expect when ordering cold drawn bars. Cold drawn steel bars cost more than hot rolled steel bars of the same grade, due to cost of manufacturing as well as yield loss in the manufacturing process. However, the benefits afforded to our precision machining shops are the absence of hard abrasive oxide scale, improved mechanical properties which lead to better machinability, improved dimensional
control, concentricity, surface finish and straightness. It is easy to see that the benefits of using cold drawn steel
bars outweigh their increased cost of production. Careful handling will preserve surface finish and straightness, minimizing perishability of quality. It is no accident that cold drawn steel bars are a preferred material for many precision machined components. Now you know some of the reasons why.
Author
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
PMPA Craftsman Cribsheet #116:
Twist drills for success
Drilling holes is one of the most fundamental operations we do in machining.
Published June 1, 2023
By David Wynn, Technical Services Manager, PMPA
In today’s world it seems that all information is tailored toward carbide drills. Carbide drills are great, but how many do you really use every day? Especially in our small-to-medium quantity job shops? It is likely that we use mostly standard HSS twist drills. It is not economical to buy expensive carbide drills for shorter-to -intermediate runs. The problem is that most of the available data and recommendations are tailored toward carbide drills. It is important that we still understand the basics of twist drills. How do you know when to use what type of drill? What is the geometry you want to have? What type of flute do you want to use?
In carbide drilling it is recommended to pilot instead of spot drilling. On the other hand, with standard twist drills it is generally recommended that we spot drill. Following with
angles that are greater than or equal to the last drill point. For instance, follow a 90-degree spot with a 118-degree drill. If you drill with a 135-degree parabolic you can’t follow
with a 118-standard drill – it will walk off center. This can be especially important for parts with multiple ID dimensions, and using non-carbide drills.
When drilling in tougher materials such as stainless, high-carbon steels and most alloys, multifaceted grinds help reduce the cutting forces at the tip and help to pull the chip. This is where parabolic drills shine. Today almost all parabolic drills are made with split points allowing them to be self centering. I have found that it is better to spot drill even when using a split point drill. The parabolic drill allows chips to flow out of the hole rapidly while still allowing coolant to reach the tip.
If the hole is greater than 3 to 4 times the drill diameter, I would recommend pullouts. With HSS twist drills, pull all the way out of the hole to allow the coolant to flood the hole and remove chips. This will also allow the tip of the drill to cool before reentering the cut. On CNCs with modern G83 peck cycles, I like to pullout to .100” in front of the hole. There is a small dwell on the pullout of the peck cycle, but if you are drilling tough material it would be beneficial to increase the dwell. Write your own cycle-increasing dwell times. Also, you can get the optimum pullouts going 3.5x drill diameter first peck, 2x drill diameter on the second peck then about 1x drill diameter (1-1.5x diameter) on all pecks after the second peck. The deeper the drill goes the more difficult it is to remove chips and get coolant to the cutting tip.
It is not recommended to try to achieve tolerances less than +/-.002 without reaming or boring. Here are some recommendations for twist drills for different materials often machined in our shops. In the light metals and those having high thermal expansion, it is recommended to use standard drills because holes cut tight. See chart below.
PMPA Speaking of Precision Podcast:
Preview of the 2023 Mastery Program
Miles Free, Carli Kistler-Miller and David Wynn give our listeners a peek into at what to expect on PMPA’s upcoming Mastery Program including five PMPA member shops, four machine tool/equipment builders, two toolmakers, one steel mill, one bar grinder, one machine monitoring company, one CAD CAM company, one industry media company, one electroplater and one metalworking fluid compounder.
Published May 29, 2023
BREAKING NEWS
Waters of The United States – Clarity for Our Shops
The United States Supreme Court just released their opinion on Sackett v. EPA written by Justice Alito. The opinion was unanimous, with other justices submitting concurring opinions while also arguing against certain points made in the Court’s opinion.
The opinion narrows the reading of the Clean Water Act- determining that the law only extends to wetlands that have a “continuous surface connection” with regulated waters of the U.S. (a relatively permanent body of water connected to traditional interstate navigable waters). This clarifies and objectively defines what is in fact a “water of the United States,” eliminating the ambiguity of the prior language and enforcement.
FULL SACKETT ET UX. v. ENVIRONMENTAL PROTECTION AGENCY DOCKET