With 84 companies responding, the PMPA Business Trends Index in March roared in from February’s 122 to a seasonally correct but record breaking 138. We don’t expect to use Santa references in our professional writing in March, but based on that strong 138 showing we “checked our list twice.” No anomalous entries. Nobody keying in an extra digit in sales. Ten shops reported sales increases of 40% or more.

New Record!
New Record!

At 138, our index is 7 points above our October 2014 record of 131, a five percent (5%) increase in reported sales by our respondents. Adding to the credibility of this “Lion Market” indicator, you will find our article in the May issue of Production Machining “Prosperity In 2015: If You Dare” that reviews the very positive economic forecast by Brian Beaulieu of ITR given at our Management Update meeting.
Also corroborating our report is Steve Kline Jr.’s March Gardner Business Index Report:
“With a reading of 54.3, the Gardner Business Index showed that the production machining industry expanded for the second month in a row and at its fastest rate since June last year. The industry clearly has been trending up since November. The industry has expanded 3 of the previous 4 months… New orders grew for the third time in 4 months. Growth in new orders has been quite strong the previous 2 months. Production increased for the 15th consecutive month. The index has been on a significant uptrend since December, and it is at its highest level since June 2014.”
Bulls? Bears?
Nope! In like a LION. Do you dare to manage for prosperity in 2015?
 March 2015 PMPA Business Trends Report

April 2015  |  Craftsman’s Cribsheet #31


Unleaded brasses are not necessarily harder to run than leaded brass. They are just different. By recognizing and accommodating for their lack of lead, and the resultant different thermal conductivity, differences in chip forming and the need to up-tool for heavier feeds rather than higher speeds, your shop can be successful at making parts from these newer, more challenging grades.



The methodology of measurement and what is measured are quite different. this is critical to understand if  you will not be paid for your parts because the Ra you measured is not in fact the Rz surface profile that customer specified.
Ra is calculated by an algorithm that measures the average length between the peaks and valleys and the deviation from the mean line on the entire surface within the sampling length. Ra averages all peaks and valleys of the roughness profile and then neutralizes the few outlying points so that the extreme points have no significant impact on the final results.
Rz is calculated by measuring the vertical distance from the highest peak to the lowest valley within five sampling lengths, then averaging these distances. Rz averages only the five highest peaks and the five deepest valleys—therefore extremes have a much greater influence on the final value.”- George Schuetz, Modern Machine Shop
RA Rz Swedev
“Ra is the arithmetical average value of all absolute distances of the roughness profile from the center line within the measuring length. Rz is the average maximum peak to valley of five consecutive sampling lengths within the measuring length.  Ra averages all measurements and does not have any discriminating value in separating rejects from acceptable cylinders.”- Swedev
And by the way the definition of Rz has also changed over the years. Which definition of Rz exactly is your customer using? How do you know?
You will find “Conversion Ratios” on the internet provided by well meaning people. But how useful can these be when the range said to be equivalent goes from 4:1, to 7:1 to 2-:1?
4:1 is equivalent to 20:1? Really? Not in my math class!
Smart shops will avoid using these “approximations in name only” and communicate with their customers to determine the customer’s true need. Gambling on conversion factors that you found on the internet is not professional, it is an example of poor engineering practice, and it fails to serve and protect your customer.
Don’t Do It!
Read this well written, not terribly mathematical treatment of the subject on MMSOnline
It’s a classic.
Authoritative standards : Surface finish measurement procedures, general terminology, definitions of most parameters and filtering information can be found in American Standard ASME B46.1 – 2009, Surface Texture, and in International Standards, ISO 4287 and ISO 4288.