A Guide to Scribe Marking

Pryor marking machines can mark a very wide range of work pieces using a variety of different character styles, sizes and depths. This guide outlines how to get the best out of your equipment. It covers Scribe marking. Other marking technologies available from Pryor are dealt with in separate articles in our knowledge centre.

A .pdf version of this guide is available to download and print.

Scribe Marking

Scribe marking uses a pneumatically driven pin which is driven into the metal surface to be marked. It is then moved through the metal, engraving the required inscription. It therefore gives a continuous engraved line. 

Fixturing

IMPORTANT - Unless the work piece is held firmly then there is little hope of obtaining a good quality mark. Scribe machines in particular require very firm fixturing as the lateral forces involved are very high during the marking process.  

If you have a wide variety of work pieces to mark then you may have to make several interchangeable fixtures.   Use a magnetic chuck, or similar, to allow these fixtures to be changed over quickly and accurately. 

Work piece material

The machines may mark a very wide range of materials but some materials are easier to mark than others.

The harder the material, the shallower the depth of mark will be.  The type of material will also influence the life of the stylus, the stylus tip will wear or chip quickly the harder the material. The angle of the stylus tip may be changed to reduce the chance of chipping. Changing the angle may also increase the readability of the mark.

Surface finish

Smooth, well finished work pieces are easier to mark than rough, scaled work pieces.  The worse the finish, the deeper the mark will have to be to remain readable.

Painted work pieces may be marked but the paint may chip, try changing the stylus tip angle to reduce the chipping.

Work piece flatness

The machine can mark on surfaces which are not completely flat but the depth of the mark will vary across the surface. Dot Peen marking can cope much more effectively with curved or contoured surfaces and can be used in conjuction with a circumferential, rotating fixture.

Marking gap

Although the machine will mark with the tip anywhere between 0.5mm and 7mm from the work piece, the recommended distance of the stylus tip from the work piece is between 3mm and 4mm.

Depth of mark

Light marks are easy to produce on most materials.   Deeper marks are the more challenging marks. Large characters can be produced to a greater depth than small ones.

The four factors which most influence the depth of a mark are:

1. Material being marked
2. Marking force (Air Pressure Setting)
3. Stylus Tip Radius
4. Stylus Tip angle

Having decided on the tip radius and tip angle to suit the material being marked, the depth of the mark is most easily adjusted by varying the marking force.

Marking force

The marking force is controlled by adjusting the air pressure. Increasing the air pressure, increases the marking force.

As a starting point, the air pressure should be set to 45 psi.

Warning: Do not turn the air pressure up too high. If the stylus is driven too hard into the material it can stick in the material and cause the motors to stall producing a bad mark. If the machine is stalling try reducing the air pressure or reducing the marking speed.

Stylus tip Radius

This is normally determined by trials on the material prior to delivery of the machine. Typical radii are between 0.5mm and 1mm.

Generally, the smaller the radius, the deeper the mark, but small radii can lead to tearing of the material instead of forming it.

Larger tip radii give wider marks.

Stylus tip angle

The standard tip angle for the carbide tip is 110 degrees included. This can be modified for special applications if required.