Spring alignment dowelsbushings

1

SPRING ALIGNMENT DOWELS/BUSHINGS

2

Spirol’s roll formed hardened bushings are designed to meet oneor more of the following objectives:

� Align mating components,� Eliminate drilling of a separate bolt hole,� Protect bolts from shear loading, and/or� Maintain joint integrity

Although these hollow, lightweight bushings are not precision groundand do not require precision holes, thus saving in component and holepreparation costs, they are capable of precision alignment if the designguidelines are followed. Further savings can be achieved by using theinside of the dowel bushing for the bolt and thus eliminating the cost ofa separate bolt hole. This design concept also protects the bolt fromshear loads perpendicular to the bolt and isolates the forces on the boltto tension loading. Shear forces acting on a bolted joint cause the jointmembers to slip back and forth, which causes the bolts and nuts torotate, reducing the pre-load tension. This is particularly the case withshort bolts with a reduced clamping distance.

SPRING ALIGNMENTDOWELS/BUSHINGS

CHALLENGE US!

3

SPRING ACTION

The diameter of the bushing is slightlylarger than the hole. The spring actionof the bushing allows it to be installedinto a drilled or cored hole and assumethe diameter of the hole. It is self-retained once installed.

PRODUCT FEATURESAND BENEFITS

CONTROLLED INSIDEDIAMETER

The inside diameter of the dowelbushings is designed to provideclearance for a bolt through the bushingfor the purpose of fastening the alignedcomponents together. This isolatesthe bolt from the shear loading andincreases the joint integrity. It alsoeliminates the cost of a separate hole.

STAGGERED SEAM

The staggered seam preventsinterlocking, making these bushingssuitable for automatic feeding andeliminating the need to separate themduring manual assembly.

LEAD-IN CHAMFERS

The beveled chamfer around the entireperiphery of the bushing is designedto facilitate ease of insertion and toavoid skiving of the bushing duringinstallation.

4

SPRING ALIGNMENTDOWELS/BUSHINGS

Spring alignment dowels are used to accurately locate components with respect toeach other. They are formed around arbors to assure roundness. It is recommendedthat one half the hole tolerance be used for the fixed location of the dowel and one halffor the hole in the mating part.

Dowel bushings are used to locate components in conjunction with bolts which passthrough the inside of the bushing after it has been installed. Separate holes for locatingpins are eliminated. The hardened bushings also absorb shear loads, isolating the boltsfrom these forces.

Part Number: Product Type, Size x Length, Material, Finish, SeriesExamples: BUSH .250 x .500 BK DB100 BUSH 10 x 20 BT DB100 BUSH .500 x 1.250 BK SD200 BUSH 10 x 20 BR SD200

L

O.D.

Standard Lengths Note: .750” size does not require a staggered seam pattern to prevent interlocking.Larger and special diameters are available upon request.

The chamfer on dowel bushings and spring dowels is designed to facilitate insertion into minimum specified holes.

Series DB100 - Dowel Bushings

Max..255.318.396.474.630.786.937

Length

Min..250.313.391.469.625.781.932

Min..260.323.401.479.635.791.942

Max..270.333.411.489.645.801.952

.022

.028

.035

.042

.057

.070

.083

1,660 lbs.2,670 lbs.4,200 lbs.6,070 lbs.

11,050 lbs.16,500 lbs.23,300 lbs.

Min.SingleShear

NominalBolt

Diameter

O.D.Tolerance Range

for Holes WallThickness

#10.250 1/4.312 5/16.375 3/8.500 1/2.625 5/8.750 3/4

.3753/8

.5001/2

.7503/4

1.0001

1.5001-1/2

1.2501-1/4

INC

H

1.7501-3/4

LENGTH TOLERANCE+.000" -.030"

7.4 kN11.4 kN18.7 kN28.5 kN46.5 kN56.1 kN73.5 kN

MinimumSingleShear

5mm6mm8mm10mm12mm14mm16mm

LengthNominalBolt

Diameter

O.D.Tolerance Range

for Holes WallThickness

Max.6.868.18

10.4413.0115.6017.9020.35

Min.6.607.92

10.1812.7515.3417.6520.10

0.560.710.891.071.451.551.78

10mm 12mm 25mm 30mm 35mm 40mmMax.6.487.80

10.0612.6315.2217.5519.95

Min.6.357.679.93

12.5015.0917.4019.85

ME

TR

IC 20mm

LENGTH TOLERANCE+ 0.0mm - 1.0mm

Series SD200 - Spring Dowels

Max..255.318.380.505.630

Length

Min..250.313.375.500.625

Min..260.323.385.510.635

Max..270.333.395.520.645

.022

.028

.035

.042

.057

1,660 lbs.2,670 lbs.4,000 lbs.6,530 lbs.

11,050 lbs.

MinimumSingleShear

NominalDowel

Diameter

O.D.Tolerance Range

for Holes WallThickness

.250 1/4

.312 5/16

.375 3/8

.500 1/2

.625 5/8

.3753/8

.5001/2

.7503/4

1.0001

1.5001-1/2

1.2501-1/4

INC

H

LENGTH TOLERANCE+.000" -.030"

6.9 kN11.9 kN18.9 kN27.2 kN49.6 kN

MinimumSingleShear

LengthNominalDowel

Diameter

O.D.Tolerance Range

for Holes WallThickness

Max.6.58.5

10.512.516.5

Min.6.258.25

10.2512.2516.25

0.560.710.891.071.45

10mm 12mm 20mm 25mm 30mm 35mmMax.6.138.13

10.1312.1316.13

Min.68

101216

6mm8mm

10mm12mm16mm

ME

TR

IC

LENGTH TOLERANCE+ 0.0mm - 1.0mm

MATERIALB Carbon Steel AISI 1070-1080

DIN 177222 CK67-75BS 1449 CS70-80

FINISHK Plain, OiledT Zinc PlatedR Phosphated, Oiled

INSPECTION METHODSO.D. - MicrometerLength - Caliper

HARDNESSHV 420-545

5

Doweling for Permanent Positioning

If components are located or positioned by methods otherthan the doweling itself, and the issue is to allow fordisassembly and then re-assembly with the componentsin exactly the same location – then it is recommended thatthe components be drilled together and the dowel installedin the assembled condition. During disassembly, the dowelmay be removed and reinstalled during re-assembly. Thismethod eliminates the need for hole tolerancing and holecenterline concerns. It provides for very accuratepermanent locating.

DESIGN GUIDELINES

Doweling to Fix Relative Location Of Components

The more common application is to use the dowels to fix the relative location of two or more components. In this situation,the dowels are partially installed in one component, the initial installation, and then holes in the mating component arepushed over the exposed end of the partially installed dowel. The following factors need to be considered for precisionlocation:

� Hole dimension tolerance

� Relative depth of initial installation

� Total length of the bushing

� True position of hole centerlines

These factors are interrelated and need to be considered together. The following general guidelines are helpful indetermining the best design in a specific situation.

� Precise holes with reduced hole tolerances increase the cost but also increaselocation accuracy and simplify the design considerations.

� Wider hole tolerances require longer dowels to assure a tight, non clearance fit inboth components.

� Hole tolerance should be minus in the initial installation hole and plus in the matingcomponent hole.

� The maximum hole tolerance should not exceed one half (1/2) of the recommendedtolerance range to allow for hole tolerancing of both holes within the tolerance range.

� Fixing the dowel location in a through hole can be achieved through length ofengagement and hole tolerancing, or both. Generally, an engagement of 60% ofthe total length in the smaller hole is recommended for the fixed location.

� If more than one dowel is used, holes in the upper recommended tolerance rangeallow for a wider tolerance in centerline location.

6

DESIGN GUIDELINES

Precise Holes

If the holes are precise and the same in bothcomponents, such as honed or reamed holes with atolerance of .0008” or .002 mm, then the length of thebushing need only receive minor consideration forpurposes of precise relative location. We recommendusing the minimum specified hole in these situations.The bushing will assume the diameter of the initialinstallation hole and the unsized diameter of thenormally exposed end would compensate for thetolerance difference between the holes if any. If nointerference whatsoever is acceptable whenassembling the mating component over the exposedbushing, then it is recommended to keep the exposeddowel length to a minimum, or if practical, to push thedowel through the initial component to size theexposed end. In any event it is recommended toinstall at least two thirds of the total dowel length intothe initial hole so as to permanently fix the dowelposition.

Maximum Tolerance Holes

The maximum allowable tolerance is one-half thetotal recommended tolerance. This is still within thenormal production hole tolerance for drilled or coredholes. The smaller hole, that is the hole with theminus tolerance, should be the hole into which thedowel is initially installed. The larger hole, that is thehole in the mating component, should have a plustolerance. To illustrate: The total recommendedhole tolerance for an 8 mm dowel is 8.00 to 8.13.Take the approximate midpoint and split thetolerance. The smaller hole would be 8.00 to 8.06,the larger 8.06 to 8.13. The smaller hole used for theinitial installation will size the dowel but the protrudingunsized length of the dowel remains larger, with thediameter increasing as the distance from the holeincreases. It normally requires a protruding lengthequal to 1-1/2 times the dowel diameter for a dowelinstalled in a minimum hole to have a protrudingdiameter greater than the maximum hole. For an 8mm dowel in a 8 mm hole, that would require aprotrusion of 12 mm to have a dowel diameter at theprotruding end greater than 8.13 mm. The smallerhole in the initial installation helps in fixing thelocation of the dowel but it is still recommended thatthe greater length of engagement be in the smallerinitial hole. Therefore, in the example used here toillustrate the maximum hole tolerance situation, thedowel would be BUSH 8 x 30 BK SD 200.

EQUAL TO HOLE DIAMETER

≤ 1 OUTSIDE DIAMETER

≥ 60% OFDOWEL LENGTH

TOTAL HOLE TOLERANCE = ∅8.00 to 8.13 mmHOLE FOR FIXED DOWEL LOCATION = ∅8.00 to 8.06 mmMATING COMPONENT HOLE = ∅8.06 to 8.13 mm

∅8.13 MINIMUM (MAXIMUM HOLE DIAMETEROF MATING COMPONENT)

12 mm

18 mm

∅8.00 (SMALLEST DIAMETERWITHIN TOLERANCE)

7

Centerline Tolerancing

If more than one dowel is used, centerline tolerancing forhole positioning becomes an issue. In situations with

precision holes requiring precision locating, thecenterline tolerancing needs to be accurate andsimilar to tolerancing used for solid dowels. A

tolerance of .0006” or .0015 mm is recommended.When a dowel is installed in a minimum hole, which

is recommended in these cases, the dowel gap isbutted and further spring action is very limited, if any.

Hole tolerance can be increased to provide for relaxedpositioning tolerances with some sacrifice of rigidity. The

centerline tolerance can be increased to the tolerance ofthe holes, or the smallest tolerance if the tolerances of the

holes are different. In the 8 mm dowel example used,the centerline tolerance can be .06 mm. The net holeat maximum misalignment cannot be less than thesmallest recommended hole; in the example, 8 mm.The misalignment will normally distribute itself

between the dowels.

If it is a dowel bushing application with a bolt passingthrough the dowel into a threaded component, the clearancebetween the minimum inside diameter of the dowel bushingand maximum bolt diameter needs to be enough tocompensate for misalignment. If these guidelines areused, the standard clearance will always be adequate atmaximum misalignment.

SPIROL APPLICATION SPECIALISTS ARE AVAILABLE TO MAKE RECOMMENDATIONSBASED ON YOUR REQUIREMENT OR TO REVIEW YOUR APPLICATION.

Blind Holes and Stepped Holes

Blind and stepped holes can be used for dowel location and stepped holes are generally used for dowel bushings usedin conjunction with bolts. Since blind and stepped holes only fix the dowel location in one direction, it is still recommendedthat the dowel be fixed into location by using the smaller hole and greater length of engagement.

Joint Integrity

Loss of joint integrity due to rotational loosening is triggered by vibration. Loads perpendicular to the axis of the bolt,particularly cyclic loading cause slip at the bolt head or the nut which translates into rotational loosening. Dowels,particularly dowel bushings, reduce or even eliminate rotational loosening. In this instance, the use of the smallest holepossible within the tolerance range is recommended to reduce dowel flexibility after insertion. The shear strength alsoneeds review. In static loading or a long cycle time between loads, maximum load should not exceed of 75% of theminimum shear strength. When the loads are in the form of severe vibration, 50% is recommended.

+ 0.06– 0.00

+ 0.06– 0.00

+ 0.06– 0.00

∅ D

∅ D

C

8

APPLICATIONS

ENGINE HOUSING

ENGINE CAM SHAFT CAPS

9

INTAKE MANIFOLD HOUSING

OIL PUMP ASSEMBLY

10

OIL PUMP HOUSING

TRANSMISSION SOLENOID HOUSING

11

SWITCH HOUSING ASSEMBLY

VALVE

12

I N T E R N A T I O N A L

© 2003 Spirol International Corporation 15M 06/03 Printed in U.S.A.

e-mail: [email protected]

Canada

Mexico

Europe

U.S.A. Spirol International Corporation30 Rock AvenueDanielson, Connecticut 06239Tel.] 860.774.8571 Fax.] 860.774.2048www.spirol.com

Spirol West645 East Harrison Street, Suite 100Corona, California 92879-1347Tel.] 909.473.5900 or 800.776.9528Fax.] 909.273.5907www.spirolwest.com

Spirol International Corporation Shim Division321 Remington RoadStow, Ohio 44224Tel.] 330.920.3655 Fax.] 330.920.3659www.spirol.com

Ascutney Metal Products2637 US Route 5 NorthWindsor, Vermont 05089Tel.] 802.674.6721 Fax.] 802.674.6121www.ascutneymp.com

Spirol Distribution (Distributor Customers)30 Rock AvenueDanielson, Connecticut 06239Tel.] 800.321.4679 Fax.] 860.774.0487www.spirol.com

Spirol Industries, Ltd.3103 St. Etienne BoulevardWindsor, OntarioCanada N8W 5B1Tel.] 519.974.3334 Fax.] 519.974.6550www.spirolcanada.com

Spirol México, S.A. de C.V.Carretera a Laredo KM 16.5 Interior ECol. Moises SaenzApodaca, N.L. Mexico C.P. 66605Tel.] (81) 8385 4390 Fax.] (81) 8385 4391www.spirol.com.mx

Spirol Industries, Ltd.Princewood RoadCorby, Northants NN17 4ETEnglandTel.] 44 (0) 1536 444800Fax.] 44 (0) 1536 203415Tel.] 44 (0) 8003 890034 (Distributor Customers)www.spirol.co.uk

Spirol SAS21 rue de Baconnes51430 BezannesFranceTel.] 33 (0)3 26 36 31 42Fax.] 33 (0)3 26 09 19 76www.spirol.co.uk

FREE APPLICATION ANDINSTALLATION INFORMATION

COMPRESSION LIMITERS

SPACERS and TUBULAR PRODUCTS

ISO9001:2000 Certificate No. 11168

QS-9000 Certificate No. 5981 QS-9000:1998FM 64050

ISO 9002 Certificate No. Q 09419BS 5750

CaliforniaU.S.A

ConnecticutU.S.A.

England

Canada

In addition to our full line of Spring Alignment Dowelsand Bushings, we also offer a wide selection of standardCompression Limiters and Spacers/Tubular Products tomeet your assembly requirements. Contact Spirol fordetails.

Challenge Us!