Metallography lab automation cuts testing time and labor.

Revolutionary microcomputer technology has made basic foundry metallurgical testing duties quicker and easier.

Introduction of the microcomputer in the 1980s brought about a technological revolution that has eliminated many of the time-consuming and tedious tasks often associated with materials testing. While basic metallurgical operations in foundries, for example, have remained the same, the microcomputer has played a major role in automating testing procedures.

In the field of metallography, microcomputers have led to modular instrument designs, computer-aided imaging and walk-away convenience. Whether you're upgrading an existing metals lab or outfitting a new facility, a variety of options exists for automating nearly every metals testing procedure. This article provides a rundown of some of the advancements in various lab functions.

Sectioning

There are a variety of automated and manual abrasive cutoff machines available today that can handle every sectioning need. The saws are engineered for ease-of-use, convenience, power and low-deformation cutting. The cut quality dictates whether or not the sample will yield an accurate representation of the matrix.

Operator skill continues to dictate the quality of the cut, directly influencing the amount of sample deformation. If sample cuts are made too quickly or without the correct amount of pressure, deformation can result. Automated saws have been developed to alleviate this problem, allowing the operator to program the blade pressure and wheel speed. Submerged and water jet-spray sectioning capabilities also provide a clean, low-deformation cut.

Precision saws provide extended sectioning depth with uniform thickness and good surface finish. They can also section and wafer irregular shaped pieces with a minimum of interior grain deformation.

Grinding/Polishing

Automated sample preparation is now also possible through microprocessor technology. Automatic grinder/polishers can now prepare multiple samples from the initial grinding step through the final polish. Microprocessor control of water and polishing compound dispersion, wheel speed, pressure and times helps develop the optimal method for each metal/material to be tested.

Typically, single or multiple samples may be prepared automatically. To ensure a flat, scratch-free surface, individual pistons apply pressure to each sample in the holder, eliminating the need for blanks. The pistons can also compensate for different sample heights and mount sizes.

Modular in design, these low-profile units take up less work space than their manual counterparts. Additionally, they reduce preparation time, operator involvement and the quantity of consumables used.

Mounting

Prior to testing, samples must first be mounted in polymer. Automatic, semi-automatic and manual presses are available for a variety of mount sizes and applications. Automatic presses are the choice for high-volume requirements, semi-automatic for medium, and manual presses for low-volume applications.

Automatic and semi-automatic presses offer the operator walkaway convenience, freeing up time to perform other tasks. These mounting presses have powerful heaters, cutting lead time to a few minutes. Improved cooling systems also allow the operator to handle mounts immediately and eliminate the need to drop the mount into cold water, which can lead to edge separation. If throughput is a major concern, multiple mount presses are available.

Modern mounting presses are modular, with low-profile designs, and come in bench-top and floor units. The floor units include storage space and sample preparation areas that are particularly suited to labs with little or no counter space.

Hardness Testing

Microprocessor technology has transformed the tedious, time-consuming task of hardness testing into a routine operation. Operators can choose from microhardness, macrohardness and Rockwell models - all equipped with the latest features to help simplify the testing process. Dial-load weight systems allow the operator to enter the exact amount of force to be used for optimal effect, while adjustable dwell timers provide precise penetration duration time. Integral digital displays with hardness values and conversions, digital stage micrometers and loading speed controls also enhance the speed and precision of hardness testing.

Automatic microindentation testers perform multiple indentations and measurements without operator attendance. These systems work in conjunction with an image analysis processor and personal computer (PC), and software allows operator-defined positioning of indentations and profiles, patterns, straight or offset lines, as well as visual report design and customized application layout [ILLUSTRATION FOR FIGURE 1 OMITTED]. The images are fully reproducible and the test results can be exported to other programs.

Microscopy 

Microscope manufacturers, recognizing that operator fatigue is a problem, have designed new instruments that minimize unnecessary hand movement and incorporate the principles of ergonomics. Frequently used controls are grouped together and knobs are positioned lower for easier focusing. New lens coatings and improved illumination systems have greatly increased resolution. Operators may choose from metallographs, upright microscopes (with all modes of illumination) and stereo microscopes, all of which may export images to an image analysis system or closed-circuit television.

The microscope footprint has been made smaller, without loss of stability, allowing for convenient placement of samples and ancillary equipment near the stand. The resulting uncluttered work area makes it easier for the operator to use both the microscope and the peripheral equipment. If desired, multiple workstations may be set up for group observation and discussion. The newest products for the metallography lab include systems such as Windows-based image archiving software programs that have the ability to store, edit and transmit archived images [ILLUSTRATION FOR FIGURE 2 OMITTED]. These software programs can archive up to 10,800 images via simple cabinet and folder storage systems. All images are captured in color and can be further enhanced with marking, highlighting and drawing capabilities. Notes and messages can be attached to the images, which can then be transmitted via modem and are network compatible.

Image Analysis

Today's image analysis systems also use PCs to perform quantitative analyses on samples. Used in conjunction with a microscope, they transmit sample images to computer screens, and full-color monitors provide superior imagery that can be stored on hard disk, photographed, or downloaded to a printer. Image analysis systems also allow complex routines to be programmed in a matter of minutes and recalled for use at a later time.

With software systems that can perform gray and binary image operations and feature measurements, operators can generate custom and special reports for each analysis. Typical analysis information includes area, perimeter, length, width, fiber length, aspect ratio, breadth, convex perimeter, convex roundness and ferret average. These systems can perform gray image operations and binary image operations, as well as grain size calculations.

All these products can improve your foundry lab's effectiveness, efficiency and productivity. The key to achieving these objectives is technology. Automated equipment allows virtually unattended operation, allowing the operator to simultaneously prepare/analyze other samples, getting the most from your metallography operations.