90° Square Shoulder Insert Grades and Selection Guide

APET & XPET Grade Description
Shock & Wear Resistance Uncoated (Base Grade) with Coating Description Specifications
TOUGHEST
Shock Resistance		 DMP35 Moderate wear resistance/high shock resistance. Recommended for interrupted or unstable steel, most 300 series stainless steel, high-temperature alloys and cast iron applications. ANSI C1-C2, ISO K25-K40, M25-M35
DMP353 PVD TiCN coating. Excellent wear resistance for low-to-medium operating temperatures.
DMP35-HP High-performance medium-temperature grade. Optimum performance and wear resistance in most soft steels, soft stainless steels and cast irons.
DMP357 PVD AlTiN coating. For higher-temperature applications including tougher stainless steels, high-temperature alloys and soft tool steels.
DMP35-GLH Premium high-temperature coating. Best resistance to heat for high-shock applications. Excellent for tough stainless steels, high-temperature alloys and soft tool steels.
MEDIUM
Shock and Wear		 DMK30† Micro-grain carbide providing higher wear resistance and good shock resistance for applications in tough stainless steels, high-temperature alloys, irons and many tool steels. ANSI C2-C3, ISO K15-K30, M15-M30
  DMK303 PVD TiCN coating. Excellent wear resistance for low-to-medium operating temperatures.
  DMK30-HP High-performance medium-temperature grade. Optimum performance and wear resistance in most soft steels, soft stainless steels and cast irons.
  DMK307 PVD AlTiN coating. For higher-temperature applications including high-speed machining and heat-treated materials < 44 Rc.
  DMK30-GLH Premium high-temperature coating. Outstanding performance and wear resistance in high-heat applications involving tough stainless steels, high-temperature alloys and many tool steels.
MEDIUM
Shock and Wear		 DMP30 High wear resistance/moderate shock resistance, recommended for most steel and 400 series stainless steel applications. ANSI C5-C6, ISO P25-P40
DMP303 PVD TiCN coating. Excellent wear resistance for low-to-medium operating temperatures.
DMP30-HP High-performance medium-temperature grade. Optimum performance and wear resistance in most soft steels, soft stainless steels and cast irons.
DMP307 PVD AlTiN coating. For higher-temperature applications including high-speed machining and heat-treated materials < 44 Rc.
DMP30-GLH Premium high-temperature grade. Unbeatable performance and wear resistance in high-heat applications such as higher speed machining in steels (<44 Rc) and ductile irons.
HARDEST
Wear Resistance		 DMK25 Highest wear resistance with reduced shock absorption capabilities. Micro-grain carbide provides excellent edge strength for abrasive applications in nonferrous materials. Suitable for castings, aluminum and smoother cuts in tough stainless steels, high-temperature alloys and hardened steel. ANSI C2-C3, ISO K15-K25, M15-M25
DMK253 PVD TiCN coating. Excellent wear resistance for low-to-medium operating temperatures. Good resistance to built-up edge for aluminum machining.
DMK25-HP High-performance medium-temperature grade. Optimum performance and wear resistance in most soft steels, soft stainless steels and cast irons.
DMK257 PVD AlTiN coating. Appropriate for higher-temperature applications such as high-velocity cast iron machining, tough stainless steels, high-temperature alloys and hardened steel.
DMK25-GLH Premium high-temperature grade. Unbeatable performance and wear resistance in high-heat applications such as harder steels, tough stainless steels and high-temperature alloys.

† DMK30 grades are available in XPET only.

APET & XPET Geometry Selection
APET Geometry Traits XPET Geometry
Positive/negative cutting edge with T-land Cutting Edge Positive cutting edge with a light hone and no T-land
Somewhat free-cutting; meant for higher chiploads (>.005" IPT); creates medium burr Cutting Action Free-cutting, small burr; can run at lighter chiploads (>.002" IPT)
Higher force due to negative edge; will deflect more than XPET Force Lower force due to sharper edge; less deflection
Higher heat generation than XPET; creates more heat at higher speeds Heat Less heat generated due to positive edge
Very strong cutting edge; able to withstand more shock and interruptions Strength Weaker, due to edge sharpness; not able to withstand significant interruptions
Longer edge life due to strong cutting edge; will roll more burr and wear out rather than chip out Edge Life Shorter, due to edge sharpness; may chip out if run too long
APET & XPET Grade Selection
Traits DMP35 DMK30 DMP30 DMK25
Toughness (Fracture) Very tough, able to withstand shock and interruptions Tough and hard; not as tough as DMP35, but tougher than DMK25 Tough and hard; not as tough as DMP35, but tougher than DMK25 Not as tough; may fracture in abusive applications
Wear Resistance (Edge Life) Softer carbide, will not last as long as DMK25 Good - harder than DMP35 but not as hard as DMK25 Longer life than DMP35, but shorter than DMK25 Longer edge life due to higher carbide hardness
Heat Resistance Lower heat resistance due to lower hardness of carbide Good heat resistance - more than DMP35 but less than DMK25 Higher heat resistance than DMP35, less than DMK25 Highest heat resistance
Resistance to Built-Up Edge Fair resistance to built-up edge; some buildup may occur – use coolant as a preventative Good resistance Poorer resistance to built-up edge; not typically a stainless steel grade Good resistance
Feed Capability High, due to toughness Average - less feed than DMP35 but more than DMK25 Strong feed capabilities, approx. 20% lower than DMP35 Lower, due to brittleness; run at higher speeds and lower feeds
Coolant Capability Good; toughness gives it more resistance to thermal shock Good on high temp alloys and some tough stainless steels Fairly tough; will allow machining with good coolant flow Not as high; may experience thermal shock unless coolant flow is very good
Choose the Best Grade for Your Application
Material Operating Speed Geometry 1st Choice Grade* Coolant
Free machining, low-carbon steels Low to Medium XPET DMP30-HP Air/Flood
Free machining, low-carbon steels Higher XPET DMP30-GLH Air
Medium-carbon steels, tool steels Low to Medium APET/XPET** DMP30-HP / DMK30-HP Air/Flood
Medium-carbon steels, tool steels Higher APET/XPET** DMP30-GLH / DMK30-GLH Air
All steels – interrupted cuts and heavy roughing cuts All APET DMP35-HP / DMP35-GLH Air
Heat-treated steels (48-62 Rc) Low to Medium APET DMK25-GLH Air
Soft stainless steels (303, 304) Low to Medium XPET DMP35-HP / DMK30-HP Air/Flood
Soft stainless steels Higher XPET DMP35-GLH / DMK30-GLH Air/Flood
Tough stainless steels (304L, 316, 400 series and PH series) Low to Medium XPET DMP35-HP / DMK30-HP Air/Flood
Tough stainless steels Higher XPET DMP35-GLH / DMK30-GLH Air/Flood
Cast iron All APET DMK30-HP / DMK25-HP Air
Aluminum alloys, copper alloys All XPET-ALU
XPET-PCD		 DMK25/DMK253 Flood
High-temperature alloys, titanium All XPET DMK30-GLH Flood

* Only one grade (except for aluminum) suggested. Contact Applications Specialist if first choice doesn't work.

** Customer preference. Both are acceptable – see cutting edge differences above.

Dapra 90° Square Shoulder products are made in the USA.