Shop Floor Alloy Analyzer: Material ID On The Fly

Part designers love to look through various material specification tables and charts to find an alloy that is "just right" for a given application. While that works fine for designers, the myriad of alloy options available can wreak havoc in the shop charged with making the parts.

Obviously the shop can call its supplier and order whatever alloy is necessary for the job and trust that what was ordered is what gets delivered. It has become good shop practice to check incoming materials to assure they are the alloy the supplier says they are. It's way too late to crank out a run of 100,000 parts specified to be run from ANSI 301 stainless only to find that the whole job was run from ANSI 316. Moreover, as traceability standards tighten, the documentation of incoming stock becomes step one in that process.

Generally, incoming stock is checked in a lab or lab-like area of the shop. Analysis is done with benchtop equipment that can perform spectra analysis, or some variation, that confirms the chemical composition of a sample. In part because these analyses can interrupt the flow of material, they are usually performed on incoming bundles of stock before it is racked and on a sample of complete parts before they are shipped.

However, there are many opportunities for material to get mixed up between the storage rack and the shipping floor. For example, many shops use "shorty" bar feeders. Often incoming material is cut to length before being queued in the feeder's magazine. One end of the cut bar has its alloy type marking but the severed end of the bar doesn't. This poses a possible process variable that can break the tractability chain.

A new device is available to help shops get positive material identification (PMI) anywhere in the metalcutting process at any time, within seconds. It's called the XL-800 Series alloy analyzer, and it is made by Niton (Billerica, Massachusetts).

The XL-800 Series is a family of portable analyzers that operates using non-destructive, X-ray fluorescence (XRF) technology to identify alloy samples by grade name and report their chemical compositions. It's battery operated and weighs less than 2.5 pounds.

The unit operates like a barcode reader requiring only that the reader head touch the material. In seconds, a display of the alloy grade and chemistry of the sample can be read on the unit's screen.

Three modes of operation are available to accommodate the analysis needs for various PMI needs within the shop. An alloy grade and chemistry mode gives a rapid analysis of the elemental composition and grade identification for 300 commonly used alloys. Typical testing times are 3-5 seconds for quick identification and chemistry verification. More precise chemical analysis takes 10-20 seconds.

The built-in grade library contains minimum and maximum specifications for each grade. In this mode, shops can determine relatively small variations in chemistry between different heats of the same alloy material so that machinability parameters can be adjusted.

A second mode of operation for the XL-800 series is called signature match mode. It allows sample sorting and output verification testing with very short—typically less than 3 seconds—testing time. This mode can store 250 alloy signatures for matching to various materials in process in the shop.

To reflect its specific material mix, a shop can modify the match criteria. According to the company, this mode is ideal for quickly sorting mixed loads of different alloys and alloy grade verification in high-volume production environments.

Pass/fail mode is the third way to operate the alloy analyzer. In this mode, the unit simply displays a pass/fail sample classification in less than 3 seconds. Parameters for pass/fail mode are adjustable by the shop.

Data accumulated from any of the operation modes can be downloaded to a PC for further analysis and creation of history files for traceabilty requirements. The operating software for off-line storage comes with the unit.

Besides performing analysis on raw material and work in process, this unit is able to take readings from chips and tell the makeup of each barrel of scrap before it heads out to the recycler. Portability and its wide range of analysis would seem to offer numerous material identification opportunities in a metalworking shop.

Streamlining workpiece throughput is an important drive for shop efficiency. Toward that goal, much of the inspection and quality assurance activity that once took place off-line has been re-implemented as much as possible on the shop floor.

It would seem that having the flexibility afforded by an instrument such as the XL-800 series analyzer is in step with improved throughput. From incoming stock to outgoing finished parts, uninterrupted processing of workpieces with the ability to perform PMI at any point in the flow might be worth a look.