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Flange Facing Machines: Definitions Listed A to Z


If you're an in-situ machining or flange facing facing 'newbie' - the terminology used by flange facing machine manufacturers and on-site engineers might seem a little daunting at first.  That's why we've put together this A to Z list of abbreviations and terminology which we hope will help you - whether you're trying to choosing the right machine, or if you simply want to top up your machining knowledge. Here's what we came up with listed alphabetically.

 ASME - The American Society of Mechanical Engineers. The leading international developer of codes and standards associated with the art, science, and practice of mechanical engineering. For flange facing standards - refer to ASME B16.5 Pipe Flanges and Flanged Fittings. 

Air Lubricator - A unit used with pneumatically driven flange facing machines.

Back Facing - Machining the back face of a heat exchanger flange.

Base - Internally mounted flange facing machines have a base for attaching clamping legs.

Boring - an extra operation possible with some flange facing machines. This is needed when machining grooves for Ring Type Flange Joints.

Bearing  - an important part of an internal mount flange facer. The quality of the bearing has a strong impact on the stability of the facing arm.

Compact Flange -  A type of flange common in the oil and gas industry. The compact flange has a sealing surface with a slightly angled face. To save space, it uses a sealing ring instead of a flat gasket.

Counter Balance - used with internal mount flange facers when used in the vertical orientation. A balanced machine will maintain the same cutting speed throughout a full 360 degree rotation.

Carriage - the moving block on a facing arm that the tool post is attached to.

Down Feed - the amount of travel in the Z axis. Used to apply a depth of cut.

DTI - Dial test Indicator. Used when setting up a flange facing machine to check levelling.

Drive Hub - The central unit used to drive rotation of the facing arm.

Extension - Extra legs attached to the base when mounting inside a large flange bore.

Facing - what a flange facer does. Removing  the top surface of a flange to create a fresh and flat sealing surface. 

Feed - The rate at which the cutting tool is applied to the job.

Feet - The blocks attached to the legs used to grip the internal bore. Sometimes referred to as gripper blocks.

Flank Wear - The wear taking place on the flank face of a single point cutting tool.

Gripper blocks - See 'Feet' above.

Gib Strip - wear strip/spacer used in a facing arm.

Grooves per inch - exactly as described. The amount of grooves per inch on the flange surface. The less the number the more coarse the finish is.

Gearbox - You know what a gearbox is.  In a flange facer it's used to select the direction of travel and how coarse the finish is.

Handwheel - used on the top of a tool post to apply a depth of cut.

Hydraulic drive - an option available on many flange facers as an alternative to pneumatic.

IBC - Inner bolt circle - a type of gasket use don raised face flanges.

In - The direction in which the tool post traverses towards the center of the bore. 

Jaws - Used to clamp to the flange - See Feet and Gripper blocks above.

Lubricator - same as air lubricator above.

Mast - the top of the central hub on an internal mount flange facing machine.

Machinability- As you would expect - how easy the metal is to machine - find out more in this article

Motor -available for flange facers in either pneumatic or hydraulic.

Nose Radius - on a cutting tool insert this is the radius generated at the intersection of the leading and trailing edges of the tool. A larger nose radius is needed for a wider groove.

Nominal Size - The size used on pipes and flanges for identification only and not necessarily the exact dimension. 

OD - outside diameter - example OD mount flange facing machine

Out - The direction in which the tool post traverses towards the outside edge of the flange.

Pneumatic - A drive option for a flange facer.

Power Pack - A hydraulic unit used to deliver supply to the machine.  Diesel driven and capable of operating in remote locations with no air line or electric power.

Quality - There's not too many Qs relating  to flange facing - but quality is important. If you buy a cheap machine the quality of your work will suffer. A false economy.

Raised Face - A common type of flange which required a spiral serrated finish to ensure joint integrity.

RTJ - Ring Type Joint.  These flange joint use a metal ring unlike raised face flanges which often use flat spiral wound gaskets. They are used for high pressure oil and gas applications.

RMS - Root Mean Square -  A mathematical measure of the average roughness of a surface.

Setting Straps - Used to hold the machine in place during base installation. These are removed when the assembly has been secured and is confirmed as level.

Spiral Serrated - The finish created by a flange facer. Other names are phonographic finish and gramophone finish.

Slide ways -  These are the hardened steel rails that the carriage travels across.  An important component that ensures stability of the tool post.

Surface Comparator - A handy reference kit with example surface finishes.

Swing Diameter - The dimension used to check the machine will not hit any obstructions when rotating in-situ.

Tool Post - used to hold the tooling assembly. These can usually swivel and include a handwheel to apply a depth of cut.

V -rails - same a slide ways mentioned above

Vessel - A vessel in the oil, gas and petrochemicals is used to store liquids which are often hazardous.  Vessels have flanges connected to them which need a secure joint.

Waviness - This is different to surface roughness - think of it as recurrent irregularities in the form of waves on which roughness is superimposed.

Want to find out more? Get in touch here or download our guide.

Download The Complete Guide to Managing Flanges

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