NAF Brush (Nylox) Tech Paper

Guidelines For Engineering An Effective Deburring
Solution Using Nylon Abrasive Filament Disc Brushes

Nylon Abrasive Filament disc brushes find application in deburring flat/planar part shapes with multiple surface holes, slots or cavities. Typical applications include:
Blanked steel components
Cut ends of aluminum extruded shapes
Automotive cylinder heads (intake & exhaust valve faces, combustion and block faces), and cast iron and cast aluminum components
Surface ground steel components
Powdered metal components
Any face milled or machined components
2. How Used (Guidelines):
You can implement effective deburring solutions by controlling the brush and process parameters that affect brush aggression and performance. Below are some guidelines to customize these parameters to suit your specific application.
2.A. Brush Parameters:
Tips on selecting brush parameters for effective deburring are discussed below:
2.A.1. Filament Configuration:
Tables 1a & 1b show the grit sizes and cross-sections offered in round and rectangular filaments. Rectangular filaments, having a larger cross section, are stiffer than round filaments, and therefore more aggressive. They also provide greater abrasive contact with the work surface as shown in Figure 1. Due to their smaller cross-section, round filaments are more conformable than rectangular filaments. Smaller filament cross-section in round filaments allows them to get into much smaller holes, slots and other part features better than rectangular filaments.
Table 1a: Nylon Abrasive Filament Grit Sizes for Rectangular Filaments

Table 1b: Nylon Abrasive Filament Grit Sizes for Round Filaments

Figure 1. An Illustration of Nature of Contact of Various
Filament Configurations with Work Surface
Use rectangular filaments for all applications except when:
reduced aggression is required; especially when processing softer metals such as aluminum and brass
added conformability offered by round filaments is required to accommodate a part contour
larger, rectangular cross-section cannot get into the edges of small holes/slots and other features on the part
2.A.2. Grit Size:
Use 80 grit for all applications except when:
reduced aggression is required; especially when processing delicate parts and softer metals such as aluminum and brass
generating minimal edge breaks
producing a desired surface finish
smaller filament cross-section offered in other round filament grit sizes are more suitable to get into the edges of small holes/slots and other features on the part
2.A.3. Abrasive Type:
Use silicon carbide for all general applications. Use aluminum oxide only in cases where silicon carbide causes part discoloration or raises contamination concerns on certain non-ferrous applications.
2.A.4. Brush Diameter:
Brush diameter depends on size and shape of work piece, and process/equipment
constraints such as available spindle speeds and maximum brush diameter that can
be used due to machine limitations.
2.A.5. Trim Length:
Shorter trim length means greater brush aggression, but reduced conformability. The standard 1-1/2" (38 mm) trim on Weiler disc brushes is designed to optimize aggression without sacrificing conformability for most general applications. However, in rare cases, varied trim length may be required to suit a specific application. If such a need should arise, consult the Weiler Applications Engineering Department.
2.B. Process Parameters:
Tips on selecting process parameters that optimize deburring efficiency discussed below:
2.B.1. Depth of Interference (DOI):
DOI is comparable to depth of cut in machining. Greater DOI means greater brush aggression. However, the DOI for a standard brush with 1-1/2" (38 mm) trim should be limited to .150". Using DOI beyond .150" could cause filament breakage due to excessive fatigue, leading to premature brush failure. If DOI greater than .150" is required for a specific application, consult the Weiler Applications Engineering Department.
Use .100" (2.54 mm) DOI as a starting point for all applications, and if needed, vary it within .040" -.150" (1 mm - 4 mm) to optimize aggression required to meet your application needs.
Set DOI when the brush is rotating at the operational speed.
2.B.2. Spindle Speed (RPM):
Spindle speed depends on brush diameter and DOI. Spindle speed, along with brush diameter, dictate surface speed (SFM). The following are the recommended spindle speeds for different brush diameters:

When selecting spindle speeds from the above tables,
1. using a higher spindle speed in the range will improve brush aggression
2. using a lower spindle speed in the range will enhance brush conformability
Spindle speed, influenced by DOI, is generally decreased with increase in DOI. This ensures that the spindle speed and DOI combination allow filaments to conform smoothly to part contours. Such a combination ensures that filaments are not hitting the part and bouncing off its surfaces, but are wiping and filing across its surfaces and edges. This brushing action also contributes to longer brush life. Therefore, contoured surfaces are processed at slower speeds and greater DOI than flat surfaces.
SAFETY TIP: RUNNING THE BRUSHES BEYOND THEIR MAXIMUM SAFE FREE SPEED (M.S.F.S.) RATING MAY RESULT IN PERSONAL INJURIES.
2.B.3. Feed Rate:
Feed rate is determined by the amount of deburring, edge radiusing or surface finishing required, as well as the type of material being processed. It is generally application specific. Slower feeds result in greater brushing action. Based on the brushing action desired for a specific application, feed rate can be increased or decreased.
For steel and other harder metals, use a feed rate of 18"/min.(8 mm/sec) as a starting point.
For aluminum workpieces, use a feed rate of 35"/min (15 mm/sec) as a starting point.
2.B.4. Coolants:
These brushes can be run dry, without coolants. However, certain deburring conditions such as higher speeds and greater DOI combinations can create excess heat buildup, causing the nylon filaments to melt and smear on the work surface. To overcome smearing, coolants are recommended. Coolants are also recommended when working with CNCs and other automated setups to flush the burrs/metal particles and worn abrasive grit away from the precision machine components such bearings, guides and slideways. The worn abrasive particles and metal chips in the coolants can then be trapped and removed by using a good filtration system with at least a 50 micron filter. This will minimize machine wear and tear, keep machines running clean, and keep airborne particles to a minimum. Coolants used are generally water-based.
2.B.5. Other Process Considerations:
- Number of brush stations required:
Once the brush and other process parameters are customized to provide
maximum aggression, actual cycle time required to deburr a part can be
established. If this cycle time does not meet the desired production rate,
multiple brush stations may have to be set up.
- Brush path and rotation direction: Decide brush path and rotation direction
depending on location, orientation and accessibility of burrs. Many times,
studying the path and rotation of the cutting tool that generated the burrs
can provide useful insight.
3. Engineering Your Disc Brushing Process
Select the parameters below to suit your specific application needs.
Refer to Section 2 for selection tips.
A.Filament: Round [ ] Rectangular [ ]
B. Grit Type: Silicon Carbide [ ] Aluminum Oxide [ ]
C. Brush Diameter: ___________
D. DOI: ___________
E. Spindle Speed: ___________
F. Feed Rate: ___________
G. Coolant: Yes [ ] Type ___________ No [ ]
H. # of brushes: ___________
I. Brush Rotation: Clockwise [ ] Counter-Clockwise [ ]
J. For most effective deburring, sketch the path of the brush in relation to the
part shape (roughly sketch a few options to determine the most effective path)