Abrasive

The cutting medium of an abrasivejet. Usually garnet or similar "sand like" substance.

Abrasive Flow Rate

The rate at which abrasive flows into the cutting head. Typically, abrasive is added to the nozzle from 0 - 1 lb/minute.

Abrasivejet

A waterjet with the addition of abrasive. Used to cut or machine nearly any hard material such as metal, stone, glass, etc. Other terms loosely used to mean 'abrasivejet' waterjet, water jet, water jetting, h20 jet, abrasive water jet, Aquajet (tm?), hydrojet (tm?), JetMachining®, water knife (tm?), AWJ (Abrasive water jet), UHP (Ultra high pressure) abrasive water jet.

Attenuator

An attenuator is pressure vessel that maintains output pressure for a constant water flow, compensating for uneven pressure generated by some pumps (Also called accumulator).

AWJ

Acronym for "Abrasive Water Jet" (or abrasivejet)

Bit Stream

A stream of "bits" used to control machine movements on OMAX controllers. Effectively allowing the machine to set independent feed rates at over 2000 points per inch.

C-Axis

Sometimes used to refer to a 3rd axis on the machine, such as a rotary lathe axis.

CAD (and CAD / CAM)

Computer Aided Design.  CAD software is the software that you use to make drawings of parts. CAM is Computer Aided Manufacturing.  CAM software is used to make tool paths.  Often CAD and CAM software are included in the same software package for convenience.

Catch Tank

A tank of water underneath the cutting head to allow the cutting beam to disperse, and prevent holes in your floor. Often catch tanks are filled with other material to slow the jet down, such as ceramic balls. The catch tank is also used to accumulate spent abrasive, and drop outs from your parts.

CNC

Acronym for "Computer Numerical Control".  In basic terms a CNC machine has a computer that is controlling the motion.

Intensifier Pump

A type of pump where the pressure is generated by plungers that are driven by a crankshaft.

See also Triplex Pump

Dynamic Pierce

A method of piercing a material by allowing the jet to start moving along the part path.

DXF File

Drawing Exchange Format.  This is a kind of graphical file format, defined by AutoDesk, inc., that is designed to be a common platform to exchange CAD drawing files between various CAD software packages.

DWG File

An Autocad Drawing file.  The official specification for this file format is propriatery to AutoDesk corporation, which makes it difficult for third party vendors to be compatible with it.

E-Stop

Emergency Stop. Typically a button that you press to stop the machine in the event of an emergency.

Etch

To mark the material without cutting all the way through. This is typically accomplished by reducing pressure, reducing abrasive flow rate or increasing feed rate.

Feed Rate

The speed at which the cutting head moves.

Focusing tube

See Mixing Tube.

Garnet

The most popular abrasive used in abrasivejet machining.  It is capable of cutting an extremely wide range of materials, yet is soft enough to give you long life of your mixing tube.

G-Code

Although not particularly well suited for precision abrasivejet machining, G-Code is the most popular programming language used for programming CNC machinery.

Hard Limit

A hard limit is a stop on the machine that prevents the machine from moving further in a given direction. Typically these are used to prevent the machine from moving beyond its physical limits.

See also soft limit.

Home

A spot on the machine that is defined either in software or hardware as a reference point.

IGES File

A CAD file format for exchanging CAD Drawing data between different CAD software systems.

Intensifier

A type of high pressure pump that uses hydraulics to make very high pressures.

Jewel

The orifice in which water exits to form the cutting stream. Typically jewels are made from sapphire, ruby, or diamond (thus, the name "jewel".)

Above A "jewel" mounted in a steel insert.

Jet Lag

As the cutting head moves across the material that it is cutting, the spot where the jet exits the material will lag behind the spot where it entered the material.  This lag is "jet lag".

Pictured above  The jet, as it moves horizontally, lags at the bottom of the cut.  This is why it is so important to slow the machine down when entering a corner.  Slowing allows the tail to catch up, resulting in a square corner.

Kerf

The width of the cutting beam. Typically the kerf width for an abrasivejet ranges from 0.020" to 0.060", depending on the nozzle. A waterjet has a narrower kerf, with 0.005" to 0.014" being typical.

Kick back

As the machine accelerates out of a corner that it has just cut, the jet will "kick back".

KSI

Thousands of pounds per square inch.  1 KSI = 1000 Pounds Per Square Inch (PSI)

Mixing Tube

Sometimes referred to as "nozzle" or Focusing tube.  This is a tube, made from extremely hard material, that focuses the abrasive and water into a coherent beam for cutting.

Nozzle

Usually, when someone says "nozzle" they are either referring to the complete nozzle assembly (mixing tube + Jewel + nozzle body and perhaps some plumbing.)  Other times, "nozzle" is used as a synonym for Mixing tube.

Pierce

A "Pierce" is the process of drilling through the material to be machined. Abrasivejets make their own start holes by "piercing" the material.

There are various methods for piercing

Stationary Piercing (slow on thick materials)
Dynamic Piercing (usually faster than stationary)
Wiggle Piercing (usually the fastest method of piercing)

Slat Schneidauflage

One of the supports used to support the material you are machining.  They are typically disposable.

Soft Limit

Software limit. A means of defining an area or boundary of motion for which the machine cannot exceed. Typically these are used to define the cutting envelope in which the head can move without crashing into something. This is done in software, instead of hardware, so that it can be changed when you change your fixturing or setup, and so that the machine can warn you ahead of time before you attempt to do an impossible move.

See also hard limit.

Splash back Spritzschutz

The mess that is made when you don't cut all the way through, or the jet ricochets off of a slat.  Very common during piercing, or when nozzles fail.  This is the reason you often see sponges or other guards wrapped around nozzles.

Tool Offset

Because the cutting beam of an Abrasivejet or a waterjet is not infinitely thin, it is necessary to offset the tool slightly from the geometry of the part.  For example, a typical kerf width of a nozzle is about 0.030".  If you were to trace the exact outline of the part you want to cut, the part would be undersized by 0.015", which is half of the kerf width.  Therefore, it is necessary to follow a path that is "offset" by this amount. 

So how do you measure the width of the jet?

What you do, is you cut a part of known dimensions, then measure the error.

Traverse

Normal machine movement without cutting, for example to move the cutting head into position to cut

Ultra High Pressure UHP

A term to describe the extreme pressures that are used in waterjet and abrasivejet machining. Typically pressures range from 20,000 PSI to 100,000 PSI.

Waterjet

A pressurized jet of water exiting a small orifice at extreme velocity. Used to cut soft materials such as foam, rubber, cloth, paper, etc. Sometimes people use the word "waterjet" when they really mean "abrasivejet".

Weep hole (Entlastungsloch)

A small hole drilled into high pressure fittings to allow the water to escape in a safe manner should a leak occur.

WJTA

WaterJet Technology Association.  A good source for hard core information on waterjet and abrasivejet related technology. (http//www.wjta.org)

Copyright © 2004 SPED