The Most Critical Inspections for a Crankshaft

The crankshaft in any application should be equal or better than the specifications for the original crankshaft. As an example, if the OEM called for a 2.5" main journal, plus .001 minus .002, your crank could be 2.5" minus .0005 plus .001. That would be finer tolerances than OEM, but still interchangeable in the engine. The same pattern would work for hardness, flex, smoothness or most other measurable specifications. The same would hold true for connecting rods. If you have a more specific question in mind, let us know. Good luck.

thank you for your answer but

what is the universal specification that is applied during manfacturing the crankshaft i will explain to you when you export crankshafts to certain countries they test it before they approve it and their testes are based on one of the five universal specifications ( ISO , EN , British , ASTM ... etc ) so i want to know which specification they use it to approve or reject the crankshafts

example : for approval or rejection of camshafts they use ASTM159

i want to know which specification they use to accept or reject crankshafts

In that case, you must test to satisfy "The authority having jurisdiction".

If you want to sell lumber in the U.S. you must sell it in the accepted sizes. 2X4 (actually 1.5"X 3.5", but the length would be in exact lengths. As in 2X4X8ft. Sheeting is in 4ftX8Ft sheets. When lumber is sold in Europe, it must be sized to the practices used in that country.

In the case of a crankshaft that would be used in a large commercial power producing generator, you will probably need to test for every authority having jurisdiction that you wish to sell your crankshaft in.

Try this thought on for size. Clay roofing tiles that are sold in freezing climates must not absorb more than a certain amount of water. The same tiles sold in California must be able to withstand the earthquake testing required there. That same tile needs to pass Miami-Dade County code to withstand hurricane forces. Part of that hurricane performance test requires that a minimum amount of adhesive MUST be absorbed by the tile to assure that it will not separate from the roof during severe wind conditions.

The answer is that each jurisdiction sets it's own standards. You must meet each one. Good luck.

Crankshaft is such a broad product category, it is unlikely you are going to find a universal specification that will cover all applications. For instance, a crankshaft intended for use in a commercial aircraft is most likely going to be required to conform to much more tightly defined specifications than one that is intended for use in a lawn mower motor or a water pump. You really need to be more specific about the intended application before you can even begin to evaluate specifications and design requirements...

As a quality engineer, I would refer the specification back to the drawings plus the manufacturing process reliability I then chose the critical dimensions for the inspections. About material most of OEM supplier would give you the certificate for the material they supplied if they are qualified QS9000 supplier then hardness check would give you enough info for that material

Cheers

thank you ALL or the kind replies

assume we are talking about automotive crankshaft

a crankshaft for a car

should be inspected by the folloing tests

1- hardness test lets say its hardness on Rockwell scale should be from 40 - 60

2- dimension test depending on the application

3- magnetic particle inspection for sub-surface cracks

but if there is no specification for testing this type how I can differntiate the good one from the bad ones do any one have any suggestion ??

can i cut it to pieces and every piece i perform on it different tests ??

Bob C YOU have hothing to say or give on this subject! Why bother chasing around the bush?

Thank you for explaining that to me.

Coming from such a highly decorated GUEST as yourself, it means so much to me.

From Tim Hawley Master Mech.

Hardness:

Most crankshafts are made of ductile iron because of its wear and stability at low temperatures. Hardness can vary depending on original manufactures processes. The crankshaft must be less than 58 to 60 Rockwell hardness in order to be machined with conventional carbide tool steel inserts.

See links related to (ductile iron hardness).

Tolerances for size, see links to GD&T (geometric dimension and tolerances) will differ from each manufacturer.

Manufacturing Process:

A manufacturer will reference the manufacturing cast side location pads for rotational position, clamp on each end journals and cut the centers on each end before rough turn process. Next rough turn the face surfaces, bearing journal, pulley , seal diameters, under cuts between face and journal diameters. All cross oil holes will be drilled thru each journal intersecting with main feed valley from pump. The front pulley nose and fly wheel flange will be drilled and taped. The semi finish process will finish grind the journal diameters and thrust face surfaces.

The machine operator will monitor taper, roundness and size using automatic in-process gauging integrated to the grinding machine or compensate the machine manually after grind using off line bench gauge equipment. The diameters are checked in three locations using a horse shoe off line snap gauge. The thrust face is checked for width, location and perpendicularity to crank shaft end journals centerline. The orientation-al positions will held to the manufacturers specification as far as pin journal stroke and index to the centerline of bearing journals and side manufacturing pads.

The finish operation will lap the journals to size and provide a polish finish to the thrust face as well. An in-process electronic or air gauge is integrated into the lapping machine to monitor stock removal and stop the lap process for each journal and face surface to hold size and location. Before the lap process the crankshaft will be balanced removing material from the counter weights. This is a high tech and expensive process. The workpiece is then washed and 100% inspected by and automatic final inspection gauge.

i am sorry for my ignorance but who is Tim Hawley Master Mech

Tim Hawley Master Mech Is a recent member of this site, similar to you. He has chosen to identify himself as Tim Hawley Master Mech.

Because of the short length of time that he(?) has been with us, he has not posted that many times yet. But, the posts that have been submitted so far seem accurate, intelligent, and well written.

From: Tim Hawley Master Mech.

Thanks, Bob C

Working in the Automotive, Machining, Heating & Air Conditioning and Gauging industries Across North, Central and South America gives me the edge.

Keep up the excellent work.

I would add magnetic particle inspection for sub-surface cracks.

From: Tim Hawley Master Mech.

Eddie current testing has been done on several components in the automotive industry but not on the crankshaft as far as I know.

If you know of a company that does, please let me know I will relay this information to our readers.

Thank you in advance,

Tim

there is ASTM specification that recommend to make magnetic particle test by device called electromagnetic yoke and this device make those tests

thank you ALL or the kind replies

assume we are talking about automotive crankshaft

a crankshaft for a car

should be inspected by the folloing tests

1- hardness test lets say its hardness on Rockwell scale should be from 40 - 60

2- dimension test depending on the application

3- magnetic particle inspection for sub-surface cracks

but if there is no specification for testing this type how I can differntiate the good one from the bad ones do any one have any suggestion ??

can i cut it to pieces and every piece i perform on it different tests ??

In addition to the tests mentioned, the crankshaft must also match the dynamic balance of the original crankshaft.

It would appear that you would like one centralized source for universal information. This will be unlikely to be available.

As has been pointed out, different countries/entities/jurisdictions have varying standards. You will need to investigate each's standards and tailor your product to each, either by creating unique products for each, or creating a product or products which meet several standards.

Working with a multinational manufacturer of products on a global basis, with our products distributed to many countries, I can tell you that an extensive library of regulations/specifications is needed to obtain all the information needed. A "one-stop shopping place" doesn't really exist for this. You'll need to investigate and build a data base. You will need to contact the various entities involved to request information, or do research to locate organizations who can lead you in the right direction.

I'm not an engineer, but i believe you find that each engine manufacturer will require a different set of specifications for each engine it produces. you will also find that within the same engine line the crankshaft material will vary depending on the engine application. (example) if this engine is offered in a passenger car the crank will probably be cast iron. if this engine is offered in high performance configuration or light truck it will be cast nodular iron or cast steel. finally if it is used in ultra high performance or heavy duty trucks it will be forged steel. this information is based on numerous engine builds i have completed through the years. hope this will help.

Inspection for replacement/reuse of crankshaft of any engine depends on following factors:

1 wear of Journal/crank pin dia.:If the diameters are not in permissible tolarances then go for Journal/crank pin griending with further suitable undersizes.The measurements can taken by suitable digital micrometer.

2. Check the Hardness of the crank shaft.: there are two types of harding process being used for Hardning the crank shaft, they are Induction harding & Nitriding.If hardness is not in permissible limit than do the harding process.Hardness can be tested by hardness testers which are available in the market.

3.check the straightness fo the crankshaft on lathe bed.

For maunfacturing the crank shafts always forged steel is used.

Welcome to the insanity.

From Tim Hawley Master Mech.

ENGINE, BASIC REBUILD PROCESS:

THIS MAY HELP YOU UNDERSTAND...

Dis-assembly of an engine requires all parts to be marked. Which piston came from which cylinder? and orientation is important as well. The term taking the crank down 10 10: Means removing 0.010" from the Pin and Main Journal surfaces. This is done with a precision grinder located workpiece on centers. Its a good idea to clean and debur all oil holes before and after grind process. blow air through each hole to check for obstructions. All automotive machine shops can perform this task. Auto. parts suppliers only require the engine block size and OEM (original equipment manufacturer) name and will give you a set of Bearing shells to match the new diameters sizes.

Plastic gage stock can be put between the new bearing shell and journals. Install pistons with proper piston ring orientation into each matched cylinder bores.You tighten the matched connection rod end caps to proper specifications. Install Plastic gage stock between the main bearing shells and journals and tighten the Bearing caps to OEM specifications Carefully removed each piece of plastic stock and measure with micrometers. If the clearance or plastick stock thickness is matched to OEM specifications your in good shape. If the plastic stock is pitched off the journal is too tight and stock should be remove evenly from the bearing shells at a machine shop.

Mark each bearing cap and Document all clearances. Once all clearances are achieved the thrust bearing cranshaft end play is shimmed to specifications the lower half of the motor is complete.

Important: Ask the machine shop to inspect the crankshaft first. Most re-builders will inspect all other important details of the crankshaft and inform you of potential problems before the grind process. I always check and balance the crankshaft before and after the grind process. This will tell you if there is a problem with bend of twist of the steel. Piston cylinder wear is very important and should be inspected as well as engine block deformation and wear.

Clear up something for us, please.

Are you interested in manufacturing crankshafts from stratch, or repairing/rebuilding crankshafts taken out of service to be installed in rebuilt/remanufactured engines?

This difference will play a role in the delivery of what you are working with.

Allow me to expand upon my previous post.

Are you interested in:

1) "One-off" custom regrinding/repair of crankshafts?

2) Small volume grinding repair (small production lots)?

3) Mass production of reground/repair crankshafts?

4) Mass production of new crankshafts, from raw material to finished product?

Your task impacts directly the equipment and technology you wish or need to employ.

A good answer that is to the point, always follows a specific question that is to the point!