Technical Cutter Info

Guides for safe operation and best practices.

Why use Hougen® Cutters?

Cutter Comparison Chart

What is Stack Cut Geometry?

Most Annular cutters come with Standard Geometry. These cutters are designed to cut through one piece of steel. They offer the fastest, cleanest hole while producing a slug slug that looks like a ‘Top Hat’.

When the job requires drilling two or more pieces of steel, cutters with Stack-Cut geometry must be used. The cutting teeth cut from the inside out, producing a round cylinder slug allowing you to drill trhough mulitple pieces of steel at once. Using a standard geometry cutter to drill multiple pieces, you will have to stop and remove the slug before continuing on or risk breaking your tool. RotaLoc Plus™ cutters come standard with stack-cut geometry. Most other styles of Hougen cutters are available with stack cut.

Standard Geometry Slug

Stack-Cut Geometry Slug

Number of Teeth

“12,000-Series”

DIAMETER IN INCHES	DIAMETER IN MM	NUMBER OF TEETH
7/16 - 1/2	12 - 13mm	3
9/16 - 13/16	14 - 21mm	4
7/8 - 1-5/16	22 - 34mm	6
1-3/8 - 1-5/8	35 - 42mm	8
1-11/16 - 2-3/8	43 - 60mm	10
2-7/16 - 3-1/16	N/A	6

“42/43,000-Series”
“22/23,000-Series”

DIAMETER IN INCHES	DIAMETER IN MM	NUMBER OF TEETH
3/4 - 13/16	20mm	4
7/8 - 15/16	21 -23mm	5
1 - 1-1/2	24 - 38mm	6
1-9/16 - 1-7/8	39 - 47mm	8
1-15/16 - 2-3/8	48 - 60mm	10
2-7/16 - 4	61 - 78mm	12

“53/54/56,000-Series”
“33/34/36,000-Series”
“63/64/66,000-Series”

DIAMETER IN INCHES	NUMBER OF TEETH
3/4 - 13/16	4
7/8 - 15/16	5
1 - 1-1/2	6
1-9/16 - 1-7/8	8
1-15/16 - 3-1/16	10

The Theory of Rotabroach

Other hole making techniques cut the entire hole into chips. The Rotabroach Annular Cutter hole making concept only cuts the periphery. The innermost portion or “slug” is the “energy saver”. We cut less material, make less chips. This translates into less unit horsepower. The larger the cutter, the bigger the power savings achieved.

Capacity

Extended Capacity – Higher Penetration Rates

Rotabroach Cutters clearly require less energy, what is the productivity result?

1. Extend the capacity of the machine tool by using a Rotabroach Cutter larger than the typical size restriction of conventional drills for that machine, while staying within its horsepower rating.

2. Go faster. Most users opt for this choice whenever possible. This can be done by increasing the penetration rate. Rotabroach Cutters have more teeth than conventional drilling tools.

Twist Drills – 2 cutting edges
Indexable Drills – 1 effective
Rotabroach Cutters – 3 to 12 ( on stock tools depending on the diameter)

The utilization of more cutting edges/teeth with Rotabroach Cutters allows for increased penetration rates. Small Rotabroach Cutter sizes do not possess a vast difference in power consumption, since the area factor does not provide significant power reduction. More teeth, however, are an advantage for increased feed rates for all sizes:

IPM = FPT x NT x RPM

Where:

IPM = Inches per minute penetration rate
FPT = Feed per tooth (.002-.005 IPT)
NT = Number of teeth
RPM Revolutions per minute

Even with high penetration rates, low chip loads per tooth are maintained. Forces on the teeth are kept low, reducing the tendency of tooth fracture and failure. Low thrust forces are the key element for applicability on thin walled workpieces and other nonconventional applications.

Coolant

Each Rotabroach Cutter is provided with a hole through the shank. This allows the flow of coolant through the center of the tool. A good flow of cutting fluid through the tool is important. It cools and lubricates the cutting edge, helps evacuate the chips, keeps the slug from expanding and helps eject the slug. See Hougen’s full line of lubricants including RotaMagic Concentrated Cutting Fluid

For Rotabroach Heavy Duty Industrial Cutters: A coolant system capable of delivering approximately 5 GPM at a minimum of 50 PSI is desired. Centrifugal pumps which may deliver a good flow at low pressure usually do not have the pressure capability to maintain the flow once the drill is engaged in the cut. They may deliver only a trickle in deeper holes when the coolant is needed most.

Other machine tool spindle adapters with coolant inducers are available from Hougen.

Cutting Speed

DIAMETER (INCHES)	DECIMAL EQUIVALENT	MILD STEEL	SOFT ALUMINUM	STAINLESS STEEL AND TOOL STEEL
1/4"	0.2500	1530	11920	765
5/16"	0.3125	1220	9535	610
3/8"	0.3750	1020	7945	510
7/16"	0.4375	875	6810	440
1/2"	0.5000	765	5960	380
9/16"	0.5625	680	5300	340
5/8"	0.6250	610	4770	300
11/16"	0.6875	560	4335	280
3/4"	0.7500	510	3975	255
13/16"	0.8125	470	3670	235
7/8"	0.8750	440	3405	220
15/16"	0.9375	410	3180	205
1"	1.0000	385	2980	190
1-1/16"	1.0625	360	2805	180
1-1/8"	1.1250	340	2650	170
1-1/4"	1.2500	305	2385	155
1-5/16"	1.3125	290	2270	145
1-3/8"	1.3750	280	2170	140
1-7/16"	1.4375	270	2075	135
1-1/2"	1.5000	255	1985	130
1-9/16"	1.5625	245	1910	120
1-5/8"	1.6250	235	1835	120
1-11/16"	1.6875	225	1765	110
1-3/4"	1.7500	220	1700	110
1-13/16"	1.8125	210	1645	105
1-7/8"	1.8750	205	1590	100
1-15/16"	1.9375	200	1540	100
2-3/8"	2.3750	160	1255	80
2"	2.0000	190	1490	95
2-1/16"	2.0625	185	1445	95
2-1/8"	2.1250	180	1400	90
2-1/4"	2.2500	170	1325	85
2-5/16"	2.3125	165	1490	85
2-7/16"	2.4375	160	1220	80
2-1/2"	2.5000	150	1190	75
2-9/16"	2.5625	150	1160	75
2-5/8"	2.6250	146	1135	70
2-11/16"	2.6875	140	1110	70
2-3/4"	2.7500	140	1080	70
2-13/16"	2.8125	135	1060	65
2-7/8"	2.8750	130	1035	65
2-15/16"	2.9375	130	1015	65
3"	3.0000	130	990	65

Cutting speed is the term used to express the velocity of the tool (SFM = surface feet per minute) as it cuts a specific material. Each material has an optimum range for its machinability with each cutting tool material (i.e. H.S.S. vs. carbide, etc.)

Use the following formula to compute a tool’s cutting speed:

Where:

SFM = surface feet/minute
D= tool diameter in inches
RPM = revolutions/minute

Rotabroach Cutter

SFM = .262 x diameter x RPM

Conventional Drill

SFM = .262 x diameter x RPM

Rotabroach Cutters provide a nearly constant tooth pitch. This pitch provides consistent tool life patterns for the entire range of diameter sizes in terms of lineal inches (inches of drill penetration).

Suggested Cutting Speeds

These are only starting points. They will vary with application and workpiece condition.

Feed Rates

These are only starting points. They will vary with application and workpiece condition.

Difficult-to-machine materials will require reduced feed rates.
Please contact our Engineering Department regarding specific applications.

MATERIAL OR APPLICATION TYPE	FEED PER TOOTH (INCHES)
Thin Walled Workpieces, Oblique Entry / Curved Surfaces, Semi-Circles / Fragile Setups	.001 / .002 (.003 FPT with Work Hardening Materials)
Soft / Gummy Materials	.004 / .005
Typical / Average Applications	.003 / .004
Deep Holes	.004 / .005

Hole Finish

Rotabroach Cutters provide similar hole textures as other cutting drills. Since a greater number of teeth are employed and tool life is extended, the surface finish obtained will generally be maintained longer. A slight spiral effect on the surface is noted under heavy feed rates. Light feeds and higher speeds will generally improve surface finishes.

Hole Size Tolerance

Rotabroach Cutters were originally designed as roughing tools to compete with twist drills and provide similar hole tolerance results. Many users have successfully applied Rotabroach Cutters to semi-finishing applications, reducing the number of passes from two or more to just one. A rigid machine tool and setup is required to produce holes to these specifications. Tolerances will vary with application and are impossible to pinpoint. Two hole tolerance probability curves are shown for dramatization, depicting typical results with a rigid machine tool and setup and a generalization of overall results from excellent to poor and unstable situations. Unstable conditions can lead to broken cutters.

Hole tolerance ranges are dependent on much more than the accuracy of any tool and its grind. Additionally, machine tool, workpiece, fixtures, selection of speeds and feeds, projection and type of application play an important function, determining overall results. Nominal cutter diameters are ground to a minus .001″ tolerance. On rare occasions as noted on the curves, cutters will cut undersize. This unfavorable condition will produce a burnished or reamed finish. Tool pressures can become so great that cutters may fracture. Typical reasons are:

1. If TiN coated tools are run too slowly, low friction effect allows the material to close-in.
2. Several titanium alloys and/or highly stressed materials exhibit a typical nature of closing-in on the cutter after the hole has been cut. In either case, corrective measures should be taken to eliminate the condition.

Please consult the Hougen Technical Sales Department.

Horsepower Comparison

Power consumption is a function of how fast a cubic inch of material is removed. This is broken down to area cut into chips or area factor (IN²) x how fast or feed rate (IPM) x how hard the material is to machine (K), or:

HP=(IN²) x (IPM) x K
For Steel: K=1
For Cast Iron: K=1/2
For Aluminum: K=1/4

The efficiency of a tool is also a consideration. The efficiency of the cutting edge varies only slightly with most tools and is included in the “K” factor, so its effect is negligible in most instances. TiN coating is found to be one exception where significantly greater efficiency can be realized.

This table compares the performance of Rotabroach Cutters with two conventional holemaking tools. Note the lower horsepower requirements and significantly higher feed rates of the Rotabroach Cutter.

Lower Thrust

Thrust limitations are a concern on some machine tools with larger sizes of twist drills and spade drills. Rotabroach Cutters have much lower thrust requirements, and are seldom a factor when selecting equipment. An approximate thrust force value can be determined from the following equation:

T=.7 x WT x FPT x NT Kc

Where:

T = Approx. Thrust (lbs.)
WT = wall thickness (.188, .218, .264)
FPT = Feed per Tooth (.002 – .005 ipt)
NT = Number of teeth (Divide by 2 for “Hougen-Edge” geometry)
Kc = Machinability factor as related to tensile strength

Regrindability

Because of the number of teeth and other operational benefits, Rotabroach Cutters do not require regrinding as frequently as twist drills. When sharpening, only .015″ to .020″ is commonly required if the tool was pulled at a reasonable wear point. If allowed to continue and the edge is badly worn, burned, or chipped, more material will need to be ground away.Rotabroach cutters do not have an infinite regrindability as do twist drills which can be ground back till virtually no flute exists. Hole integrity and depth is lost.

Rotabroach Cutters as well as twist drills have O.D. backtaper. As the end is reground, size is reduced. This becomes substantial when significant length is reground. Rotabroach Cutters have a limited regrind length. This length although limited, gives exceedingly long life, due to wear characteristics. By the time a Rotabroach Cutter has reached this length…it has paid for itself in increased production rates and quality of holes produced.

Regrinding Instructions

OPERATOR’S MANUAL

RESHARPENING COMPANION

PLEASE NOTE: The angles mentioned in the videos below many have changed. Please refer to the op manual above for the most up-to-date angles and settings.

Wall Thickness Chart & OD-ID

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ATTENTION: The following websites (hougentools.com & hougen-tools.com) are not authorized sellers of Hougen products and are not associated with Hougen Manufacturing in any way.

DEALER LOCATOR

Find an Authorized Dealer

Hougen products are available through thousands of trusted dealers worldwide. Use our Dealer Locator to find one near you and get the tools you need, fast.

FIND A DEALER FIND A SALES REP

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3001 Hougen Drive, Swartz Creek, MI 48473
800-426-7818

The following websites (hougentools.com & hougen-tools.com) are not authorized sellers of Hougen products and are not associated with Hougen Manufacturing in any way.

Technical Cutter Info

“12,000-Series”

“42/43,000-Series” “22/23,000-Series”

“53/54/56,000-Series” “33/34/36,000-Series” “63/64/66,000-Series”

Extended Capacity – Higher Penetration Rates

Rotabroach Cutter

Conventional Drill

Suggested Cutting Speeds

Find an Authorized Dealer

SUPPORT

CONNECT

STAY INFORMED

Find an Authorized Dealer

SUPPORT

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STAY INFORMED

“42/43,000-Series”
“22/23,000-Series”

“53/54/56,000-Series”
“33/34/36,000-Series”
“63/64/66,000-Series”