Month: March 2014

Conversion of Hardness and Tensile Strength in Steels

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Use of conversion charts and factors to convert hardness values in steels is widely done and typically based on ASTM methodology.

SAE Ferrous Materials Manual Lists ASTM E140 Standard Hardness Conversion Tables for Metals
SAE Ferrous Materials Manual Lists ASTM E140 Standard Hardness Conversion Tables for Metals

In non-austenitic steels and alloys, ASTM Method E140 Standard Hardness Conversion Tables for Metals is the authoritative standard.

  • Conversion of values is only an approximate process, due to the different combination of  material properties measured by each test;
  • Converted values are suitable for use in establishing Specification Limits;
  • Converted values are subordinate to actual test values;

ASTM Method E140 paragraph 1.12 Caveat:
”Conversion of Hardness Values should be used only when it is impossible to test the material under the conditions specified, and when the conversion is made, it should be done with discretion and under controlled conditions. Each type of hardness test is subject top certain errors, but if precautions are carefully observed, the reliability of hardness readings made on instruments of different indentation type will be found comparable. Differences in sensitivity within the range of a given  hardness scale (Rockwell B for example) may be greater than between two different scales or types of instruments. The conversion of values, whether from the tables, or calculated from the equations, are only approximate  and may be inaccurate for specific application.”
If your work requires a more detailed analysis of material hardness and correlation to mechanical properties, I recommend  “The Mechanical Properties of Work Materials” by Dr. Edmund Isakov, published by Hanser Gardner Publications.

Manufacturing Improving- February PMI Rises to 53.2 From January's 51.3

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Manufacturing Sector continues to grow and strengthen in February according to ISM PMI index, confirming PMPA’s own January Business Trends Outlook.
“Optimism in terms of demand  and growth in the near term” – Bradley Holcomb, Institute for Supply Management
“The February PMI® registered 53.2 percent, an increase of 1.9 percentage points from January’s reading of 51.3 percent indicating expansion in manufacturing for the ninth consecutive month. The New Orders Index registered 54.5 percent, an increase of 3.3 percentage points from January’s reading of 51.2 percent. The Production Index registered 48.2 percent, a decrease of 6.6 percentage points compared to January’s reading of 54.8 percent. Inventories of raw materials increased by 8.5 percentage points to 52.5 percent. As in January, several comments from the panel mention adverse weather conditions as a factor impacting their businesses in February. Other comments reflect optimism in terms of demand and growth in the near term.”
Link here
Markets the precision machining industry serves did well in February:  Machinery; Plastics & Rubber Products;  Transportation Equipment;  Electrical Equipment, Appliances & Components; Fabricated Metal Products; Furniture & Related Products; Primary Metals according to the ISM release.
The PMPA’s January Business Trends Report was similarly upbeat with strongly positive indicators for Sales, Lead Times, Profitability and Employment.
Over 59% of our reporting precision machining shops were scheduling overtime in January.
The ISM PMI Report for February 2013  shows continued growth and strength in the manufacturing sector.
proof
The ISM  report confirms  this statement with its report on commodity prices
“No commodities are reported down in price.”
That pretty much validates the index…