Team AGY

Machining S-2 Fiberglass Ballistic Armor Composites

Course: ME415

Instructor: Dr. Lamancusa

Team Members: Andrew Weaver, Charles Witt, Justin Brezovsky, Raymond Choi

Additional Information:

AGY licenses HJ1 ballistic armor to clients contracted to upgrade vulnerable vehicles. The armoring of vehicles is complicated by fitting the composite panels continuously around joints. Since an established process for machining the composite does not exist, AGY asked Penn State to design experiments to find optimized methods of making chamfer and step cuts

In general high spindle speed and low feed rate allow the cutting tool to make more cuts instantaneously on a given spot. The focus of cutting should be on the glass fibers because the resin of the armor cuts easily, but the glass fibers tend to fray out and cause abrasion on the tools. Coolant is a necessity because it carries heat away from the cutting tool and dramatically reduces harmful airborne particulates. Down cutting compresses loose glass fibers against the resin matrix for better cutting.

Step Cut
Onsrud #67-021DFC	Expected Quality	Optimum Conditions for Cut Quality
(Click to Enlarge)	(Click to Enlarge)	Tool	Onsrud Tool #67-021DFC
		Spindle Speed	12000 RPM
		Feed Rate	100 ipm
		Coolant	Flood (Partial Synthetic 15% / Water 85%)
		Direction of Cut	Down-milling

Kennametal Tungsten Carbide Face Mill	Expected Quality	Optimum Conditions for Cost Effectiveness (High Volume Manufacturing)
(Click to Enlarge)	(Click to Enlarge)	Tool	Kennametal Tungsten Carbide Insert Face Mill Insert(x3): TEEN322J-K313 Tool: KHVR25TE30C
		Spindle Speed	1800 RPM
		Feed Rate	100 ipm
		Coolant	Flood (Partial Synthetic 15% / Water 85%)
		Direction of Cut	Down-milling

1/2 inch High Speed Steel 2 Flutes End Mill	Expected Quality	Optimum Conditions for Cost Effectiveness (Limited Production < 10 Linear Feet)
(Click to Enlarge)	(Click to Enlarge)	Tool	1/2 inch High Speed Steel 2 Flutes End Mill
		Spindle Speed	2400 RPM
		Feed Rate	9 ipm
		Coolant	Flood (Partial Synthetic 15% / Water 85%)
		Direction of Cut	Down-milling

Chamfer Cut
Kennametal Single 45° Tungsten Carbide Insert Mill	Expected Quality	Optimum Conditions for Quality and Cost Effectiveness
(Click to Enlarge)	(Click to Enlarge)	Tool	Kennametal Single 45° Tungsten Carbide Insert Mill Insert: TPGM2151-K313 Tool: KIPR027TP2145
		Feed Rate	70 ipm
		Coolant	Flood (Partial Synthetic 15% / Water 85%)
		Direction of Cut	Down-milling

Cemented carbides are the optimal cutting material for HJ1 armor. Diamond tools are expensive and do not provide a dramatically better cut, although they do substantially increase tool life. High speed steels may be used, however due to the low feed rate needed for optimal cutting this may not be applicable for larger companies.

Two parameters were initially chosen to diagnose cutting conditions: tool wear and surface finish of the work piece. Composite surface finishes vary greatly because of the differing materials. Thus, average surface roughness of the cutting surface does not represent cutting conditions accurately. Instead, the length of glass fiber fray generates a better representation of cutting parameters.

Tool donations by:

Final Report

Printable Conditions Pamphlet

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