For engineers who already know the math—but still lose projects. For the last few years, I’ve been sharing technical guides here on Mechanical Design Handbook —how to size a motor, how to calculate fits, and (as you recently read) how to choose between timing belts and ball screws. But after 25 years in industrial automation, I realized something uncomfortable: Projects rarely fail because the math was wrong. They fail because: The client changed the scope three times in one week. A critical vendor lied about a shipping date (and no one verified it). The installation technician couldn’t fit a wrench into the gap we designed. University taught us the physics. It didn’t teach us the reality. That gap is why I wrote my new book, The Sheet Mechanic . This is not a textbook. It is a field manual for the messy, political, and chaotic space between the CAD model and the factory floor. It captures the systems I’ve used to survive industrial projec...
Introduction to Tool Steels
As the designation implies, Tool Steels serve primarily for making tools used in manufacturing and in the trades for the working and forming of metals, wood, plastics, and other industrial materials.
Advertisement
Tools must withstand high specific loads, often concentrated at exposed areas. They may have to operate at elevated or rapidly changing temperatures and in continual contact with abrasive types of work materials. Furthermore, they are often subjected to shocks or other varieties of adverse conditions.
%20end%20mill%20cutter%20carving%20through%20block%20of%20aluminum.png)
Figure 1: Tool steels must maintain their cutting edge even under extreme heat and friction.
Nevertheless, when employed under circumstances that are regarded as normal operating conditions, the tool should not suffer major damage, untimely wear resulting in the dulling of the edges, or be susceptible to detrimental metallurgical changes.
Tools for less demanding uses, such as ordinary handtools (hammers, chisels, files, mining bits, etc.), are often made of standard AISI steels that are not considered as belonging to any of the tool steel categories.
Heat Treatment and Composition
The steel for most types of tools must be used in a heat-treated state, generally hardened and tempered, to provide the properties needed for the particular application. The adaptability to heat treatment with a minimum of harmful effects—which dependably results in the intended beneficial changes in material properties—is a critical requirement that tool steels must satisfy.
To meet such varied requirements, steel types of different chemical composition, often produced by special metallurgical processes, have been developed. Due to the large number of tool steel types produced by the steel mills (often with proprietary designations), it can be difficult for the user to select the most suitable type without specific manufacturer recommendations.
Advertisement
The Properties of Tool Steels
Tool steels must possess certain properties to a higher than ordinary degree. This makes them adaptable for uses that require the ability to sustain heavy loads and perform dependably even under adverse conditions.
The primary trade-off in selecting a tool steel is usually between Hardness (wear resistance) and Toughness (shock resistance).
Figure 2: Design tips to reduce stress concentrations and prevent breakage during heat treatment.
The extent and types of loads, the characteristics of the operating conditions, and the expected performance (duration and consistency) are the principal considerations. These must be balanced with cost to govern the selection of tool steels for specific applications.
Although it is not possible to define and apply exact parameters for measuring significant tool steel characteristics, certain properties can be determined that greatly assist in appraising suitability. For detailed data, refer to the Machinery's Handbook.
Comments