HAND and POWER TOOL CLEANING
Hand Tool Cleaning uses non-power tools to remove loosely adhered material from a substrate. These materials include loose rust, mill scale, and paint. The tools will not remove rust or mill scale that is tightly adhered to a surface.Types of hand tools include chisels, scrapers, wire brushes, non-woven abrasive pads, and hammers.
These types of tools are used only for jobs that are difficult to get to or those where power tools are inaccessible. The process is slow and time consuming, and is therefore not used for large areas. Hand tools do not always prepare the surface to the specified roughness. SSPC-SP-2 Hand Tool Cleaning, is the specification for the use of these tools. The standard details the use of hand tools for sanding, scraping, chipping, and impacting.
Hand Power Tools
Hand power tools are portable automatic devices used for surface preparation. There are many different electric or pneumatic power tools that can be selected for various uses. Most hand power tools can be broken down into three basic categories
- Impact cleaning tools
- Rotary cleaning tools
- Rotary impact cleaning tools
Tools from these three categories have unique properties and characteristics that allow them to adapt to many different surfaces and uses. Each tool must be selected carefully, to produce the adequate roughness of the substrate. SSPC-SP-3 Power Tool Cleaning, is the specification for the use of these power tools. The standard details the removal of rust scale, mill scale, and loose paint and rust through the use of power wire brushes, power impact tools, power grinders, and power sanders. These categories will be discussed in greater detail below.
Impact Cleaning Tools
Impact cleaning tools generally use an internal piston to drive a hardened edge against a surface. The tools can be used for scraping and chipping away scale, rust, or paint. Chipping and scaling hammers fall under the category of impact cleaning tools. These devices use chisels for scraping and chipping away at thick deposits or rust scale, mill scale, weld flux, slag, and thick layers of old paint. When using impact tools, the operator must be careful to avoid cutting excessively into the surface or leaving sharp burrs where paint will fail prematurely. These tools must remain sharp or it is possible to drive rust into the surface. Impact cleaning tools are often not the most practical because of their ability to gouge the metal surface creating more surface preparation work.
Needle scalers are often used on irregular surfaces that need attention. A needle scaler, commonly referred to as a needle gun, is a device that consists of a group of steel needles that are struck by a piston in much the same way as the chisels.
The needles are projected out of the scaler simultaneously but will strike the surface individually and adapt to irregular surfaces. Needle guns are most effective on brittle or loose surface contaminants.
Piston scalers are another type of impact cleaning tool that is used. Piston scalers are much like scaling hammers except in their case the piston itself is also the chisel.
This limits the size and length of the device and allows use in confined spaces.
Rotary Cleaning Tools
Rotary cleaning tools generally consist of an abrasive material spinning at high speeds. These tools accomplish most cleaning jobs rapidly. Rotary tools leave surfaces fairly smooth but often leave oil or grease on the surface. A surface must be cleaned of oil and grease by solvent cleaning before using rotary cleaning tools. There are three basic types of abrasive material that is used with rotary cleaning tools
- Non-woven abrasives
- Wire brushes
- Coated Abrasives
These different types of media can be used on two types of rotary tool: straight, or right angle machines. Radial wire brushes, coated abrasive flap wheels, and non-woven abrasive wheels are used in straight machines. The right angle or vertical machine style uses cup wire brushes, non-woven abrasive cup wheels, wheels, and discs as well as coated abrasive discs.
Non-woven abrasives are available in several forms including cup, radial and discs. This type of tool does not remove the base metal but offers a constant rate of cleaning.
Wire brushes are available in different forms to fit different machines. These include cup and radial form, and knotted or crimpled bristles. Wire brushes are more resistant to wear and tear.
Coated abrasives generally come in disc form but can also be found as abrasive flap wheels, sheets, rolls and belts. These tools are abrasives coated with a resin to make them rigid. They are also given a specified amount of flexibility to provide adequate surface cleaning.
Rotary Impact Tools
Rotary impact tools combine the principles of the tools described above. These tools use centrifugal force to project cutters or hammers against surfaces. There are three types of media used for cleaning surfaces with these tools
- Cutter bundles
- Rotary hammers
- Rotary flaps
Cutter bundles, also known as stars, are essentially star shaped hardened steel washers that are grouped together on an axis and rotate individually.
These are used in surface preparation, grinding concrete, and for generation of non-slip surfaces.
Rotary flaps consist of heavy-duty flaps to which some type of shot (usually tungsten carbide) is attached. The flaps spin around projecting the shot into the surface. This breaks up old coatings and mill scale and can clean to white metal. This process is believed to leave a good anchor pattern for coating and can also be used to generate non-slip surfaces.
- P.S. Hollister and R.S. Short, “Hand and Power Tool Cleaning”, Good Painting Practice: SSPC Painting Manual Volume 1, pp. 68-74, 2000.
- “Power Tool Cleaning”, Naval Ships’ Technical Manual: Chapter 631, Vol. 2, pg. 5-6.
NAVSEA Surface Preparation Point of Contact
Mark W. Ingle
NAVSEA HQ, SEA 05P2
1333 Isaac Hull Ave
SE Building 197
Washington, DC 20376
Phone: (202) 781-3665