Engraving Cutters & Diamonds

Rotary Engraving

Description

Rotary engraving is the term used to describe engraving done with a rotating cutting tool in a motorized spindle. The tool, or cutter, cuts into the surface of the material to a predetermined depth and produces a groove of the same shape and dimension of the cutter. Rotary engraving can be performed on a wide variety of materials with plastic, brass, and aluminium being the most common in the awards industry. (click here for Anatomy of an Engraving Cutter)

Engraving Cutters 

The tools used for rotary engraving are generally referred to as “cutters.” Most engraving cutters are “half-round” tools which means the blank is split or halved on centre producing a “single-lip” tool which is one of having only one cutting edge.

The majority of the engraving machines used in the awards and engraving industry have spindles that use “top-loading” cutters. These are cutters that are inserted into the spindle from the top and are typically held in place by means of a threaded knob. This arrangement allows for easy cutter adjustments and changes. Top-loading cutters are most commonly available in 1/8”, 11/64”, 1/4”, 4mm, and 6mm shank diameters. Cutter lengths vary to accommodate machine spindles and accessories (burnishing attachments, vacuum chip removers, etc.).

Speeds and Feeds

The rate of the cutter rotation is referred to as the cutting speed, and the lateral movement is the feed rate. Each has a profound effect on the quality of the finished cut. The cutting speed is actually the measure of the distance travelled in surface feet per minute (sfpm) by the cutting edge and varies proportionally with tip size. For example, a .030” tipped cutter turning at 10,000 rpm has a speed of approximately 75 sfpm while a .060” tipped cutter rotating at the same speed generates about 150 sfpm. It is apparent then, that small cutters need to turn faster to achieve the same results as larger ones and vice versa. Cutter speed is determined primarily by the material being engraved. The following table and graph can be used as a guide.

Cutter Speed in Revolutions Per Minute

Cutter Tip Chart

Prices

Diamond Drag

The most common form of engraving in the trophy and awards industry is done using a non-rotating diamond-tipped tool to scratch lettering or designs in metal.

The process is frequently referred to as “diamond engraving,” “scratch engraving,” or “diamond drag” with the latter probably being the preferred terminology.

Diamond drag engraving can be performed on virtually all metals and in some applications, glass and plastics. In the awards industry, it is typically used as a quick, easy, and inexpensive method of engraving the pre-finished brass and aluminium plates on trophies and plaques. On colour plates, the diamond penetrates the coating and exposes the bare metal; a gold colour on the brass and silver on the aluminium. On material that has a clear coating, the engraving can be blackened with an oxidizing solution to add contrast.

Prices

Courtesy of Antartes Inc