Wear of equipment in our industry is not on most people’s minds nor check books.
There is no ROI on any of your shops’ equipment if your ablity to process chips is stopped because your chip processing system is non-functional due to a foreseeable and preventable wear failure.
Here are 6 wear abatement strategies for the world of high abrasion, high impact, 60-G force chip wringing and fluid recovery:
Make sure high wear surfaces are easily replaceable; liner, screen, top cover, discharge housing;
Make sure that abrasion resistant materials are properly specified for those parts subject to sliding friction;
Protect specific areas such as impact zones, liner, and vanes and key structural welds with hard facing;
Use Grade 1 screen material to maximize life of separation area;
Manganese steel is a choice for areas encountering both sliding and impact wear;
Nickel hardened castings can be used for critical transitions and joints in air discharge style equipment.
Just as we use specialized coatings to maximize output on our tools, selecting specialized materials for critical components in balance of plant equipment like chip processing equipment can assure durability and routine operation instead of creating another maintenance headache to add to the list.
For most of us, wear abatement strategies are limited to getting the right coatings on our tools and using the proper cutting oil. Yet we are vulnerable to wear failures in our balance of plant anciliaries such as chip wringers and processors.
In my steel cold finishing mill, I had shot blasters for removing scale from hot rolled bars. These shot blasters used 4140 Q&T hardened steel shot that literally ate the machines up from the inside out due to abrasive wear.
I remember increasing uptime and service life in my blasters by strategically placing hardfacing and upgraded components, just as the Prab strategies discuss.
I hope you never lose a shift of production because of lack of attention to high wear applications somewhere critical in your shop…
Where else in our shops is abrasive and sliding wear a vulnerability?
In North America, the AISI/SAE steel grade nomenclature system is widely used.
In this system, 4 numeric digits (XXXX) describe the base grade. The first two digits tell you whether the steel is a carbon or alloy grade. If the first digit is any number other than a “1”, that steel is an alloy steel. We’ll discuss alloy steels in a later post. If the first digit is a ” 1 “, the steel is a carbon grade. 10XX is the template for the plain carbon steels. We’ll explain those last two digits at the end of our post. (Exception: if the second digit is a “3”- then its one of the alloy manganese 13XX grades- grades we don’t encounter very often these days.) If the second digit is a “1”, the steel is a resulfurized carbon steel. 11XX. Guess how many “extra” elements were added to the grade? If you guessed 1- thats right. Sulfur is the one element added to promote machinability in the 11XX grades of steel. If the second digit is a “2”, the steel is called a rephosphorized and resulfurized steel. Both sulfur and phosphorus,-2 elements- are added to make these free machining steels. 1215 and 12 L14 are the grades we mostly see today. (As many of you know, that “L” as an infix tells us that there is a lead addition in the 12L14 steel.) If the second digit is a “5” the grade is a high manganese carbon steel. Grades 1524, and 1541 come to mind as the principal 15XX grades seen by our industry.
A “B” infix tells us that the steel has been treated with boron. This makes it especially adept at being heat treated. 15B21 is used to make fasteners that are heat treated.
So, now that you know what the first 2 digits mean in a US grade designation for steel, what about the last two?
The last 2 digits in the grade are the mean or average carbon content of the steel. In weight percent. So grade 1018, is a plain carbon steel, 0.18% average carbon content. 1144 is a resulfurized 0.44% average carbon content steel for higher strength and machining.
And 1215, well- 1215 is a resulfurized, rephosphorized 0.09 max weight % carbon steel for machining. 0.09% max! Don’t you just love exceptions?