Mounting presses and equipment are used to encapsulate specimens of a metal, ceramic or other material with a mounting compound to allow grinding, polishing and other sample preparation for analysis using microscopes, hardness testers or spectrometers. Mounting pressing, vacuum impregnation and cold casting are techniques used in mounting metallographic or material samples.

The mounting compound or resin used is determined the type of mounting press or equipment required. Edge retention is an important consideration when selecting a mounting resin. Hot mounting compounds tend to provide better edge retention compared to cold mounting resins, but they require investment in a mounting press. Samples can be mounted in cold mounting resins with loss cast mold or mold cups.

The mounting equipment should produce a sample mount with two parallel planar surfaces, which maintains focus of the polished samples surface during metallography or microscopy. Hot mounting presses tend to produce very planar samples. If samples are cold mounted on a non-level table or benchtop, then the sample mount surface planes will not be parallel and additional the grinding will be required to attain planarity.

Types of Mounting Presses and Equipment

Cold Mounting Equipment - Cold mounting equipment is used to mount samples for microscopy or other analysis using cold or liquid resins. Cold mounting resins are typically a two part system. A sample is placed in a cold mounting ring mold or dam, mold cup, or rubber molds and then the cold mounting resin is poured around the sample and cured. Some mold rings remain with the sample and cannot be reused. Silicone rubber molds are reusable because the mounting sample can be removed. Curing typically occurs at ambient or room temperatures. The lower curing temperatures and the absence of applied pressure can be useful in some biological and materialography applications with heat sensitive or delicate samples. Additional equipment for cold mounting can include vacuum degassers, mixers, dispensers, and metering or measuring devices. In some applications, a vacuum degasser is used to remove entrapped air from the resin or sample to avoid the formation of air bubble around the sample. The void formed from the air bubble would hinder sample grinding and polishing because coarser grit abrasive will collect in the pocket.

Compression / Hot Mounting Press – Compression or hot mounting presses are used to form and cure compression mounting compound around a sample. The pressure and heat applied is typically not a problem with most metal alloy, ceramic, glass or inorganic samples. The compression mounting resins are typically powdered or granular forms of thermoset resins such as diallyl phthalates, phenolics, melamines and epoxies. Some thermoplastic resins such as acrylics are used to form a clear mount around the sample, which may be useful if a specific part of the sample needs to examined. The clear resin allows the materialographer or metallographer to grind and polish down to the plane or point of interest in the sample.

Embedding Equipment – Embedding equipment is typically used for preparation and embedding of biological samples such as bone, tissue, plants or other organic matter from living or expired organisms.

Pellet Presses – Pellet presses or briquetting presses are used to prepare samples for spectroscopy or chemical analysis in a spectrometer. Potassium bromide (Br) powder is used to make Fourier transform infrared spectroscopy (FTIR) pellets. X-ray fluorescence ( XRF) samples are prepared by mixing the powdered sample with 1 to 3 weight percent of boric acid or a proprietary grinding or briquetting additive.

Melter / Dispenser – Melter or dispenser are used to Melter can include pouring pots, hot plates or heated dispensers. The melted adhesive, wax, blocking resin or mounting compound is poured around a sample or used to bond a sample to holder, which allow a larger sample to be sectioned to produce a sample small enough for mounting or microscopy analysis.

Specifications

Mold Size / Diameter– The mold size or diameter specification indicate the size or size range of mounts that the mounting equipment can produce. The size is essential the bore size or inner diameter of the hot mounting press or cold mounting mold.

Molding Pressure – The pressure applied during the mounting process

Molding Temperature – The temperature applied during the mounting process

Cooling Time - The cooling time required during the mounting process. Mounting presses or equipment with short cooling times provide higher sample throughput.

Features

Automatic / Programmable – The mounting process steps are programmable or recordable, which allows the sample mounting process to be precisely duplicated for a variety of samples.

Duplex Molding – Duplex molding allow processing of multiple samples simultaneously by place a duplexing space in the mold between sample mounts.

Manual – In mounting presses and equipment with manual feature, the processing steps are controlled by operator input.

Water Cooling – The mounting equipment has water cooling capability to speed up processing time.

Applications

• Biomaterials (Tissue, Bones, Cells, etc.)
• Ceramatography
• Failure Analysis
• Forensics
• Metallography
• Materialography
• Microelectronics Analysis
• Mineralogy / Petrology
• Optics / Lens
• Spectrographic / Spectrometry
• Wafer / Substrate Analysis

Image credits:

Wikipedia