Crack Detection & Repair
Crack Detection & Repair
Crack Detection & Repair
Introduction
The Irontite crack repair system is a cold repair process for repairing cracks in castings by adding metal and
moving the metal in the casting to close the crack.
The basic crack repair process involves:
1. Detection of the crack - including determining the location of the crack.
2. Relieving the stress in the casting in the area of the crack.
3. Adding and moving metal in such a manner as to close off the crack.
4. Refinishing the surface of the repaired casting.
This cold crack repair process does not in any way subject the casting to high temperatures of a welding
process, nor does it alter the heat treated characteristics of the casting.
Cracks in metal castings are the result of stress or strain in some part of the casting. This stress or strain finds
a weak point in that section of the casting and causes the casting to separate at the weak point.
Such stress or strain may develop from:
1. The casting having been subjected to pressure or temperature changes before it was properly aged,
or
2. Having been subjected to excessive heat or cold, or
3. Subjected to too rapid a change in the temperatures.
Whatever may have caused the stress, and in turn the crack, the important job is to relieve the stress at the
point of the crack, close off the crack and resurface the casting.
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INSTRUCTIONS
1. Clean the surface of the casting to be checked. Remove all oil, grease or other dirt from the surface of the
casting. Leave it dry.
2. Plug the magnet input cord into a nearby convenient electric outlet. Make certain that the magnet cord is
properly grounded and keep the unit away from water or other liquids when in use.
3. Position the magnet on the surface of the casting and activate the magnet with the push-button switch.
4. Using the powder spray bulb filled with magnetic powder, dust or “drift” the magnetic powder onto the
surface of the casting between the two poles or “legs” of the magnet.
The magnet creates a magnetic field in the casting, running from one pole to the other. If there is a crack in
the casting between the two poles, it breaks the field and draws an accumulation of magnetic powder, sharply
outlining the crack.
Since the magnetic powder reacts this way only between the poles of the magnet, it is necessary to move the
magnet around on the surface of the casting to check the area for other cracks and to show the full extent of
any crack.
5. When the magnetic powder shows the existence and location of a crack, the crack should be completely
marked so it can be easily identified later for the repair.
NOTE: This magnetic crack detection process can be used only on the types of castings subject to magnetic
charges. It cannot be used on aluminum castings.
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INSTRUCTIONS
1. Thoroughly clean the surface of the casting which is to be checked. It should be free of oil, grease and
moisture.
2. Spray the surface of the casting with the penetrant - Kwik-Chek #1. Allow time for the penetrant to dry -
usually about 3 minutes (more time in colder weather).
3. Spray the same surface of the casting with the remover - Kwik-Chek #3. Immediately rinse with water and
wipe clean and dry.
4. Shake the Kwik-Chek #3 Developer until the agitators rattle and then spray the surface with a very light
coating.
5. As the thin coat of developer dries, cracks and porosity on the surface of the casting will show up in red
lines or dots.
Includes:
# 1 - Dye Penetrant 400-1320-01
# 2 - Remover 400-1320-02
# 3 - Developer 400-1320-03
CAUTION: THE PROPELLANT IN THE KWIK-CHEK CANS IS EXTREMELY FLAMMABLE. When storing
or using the cans, keep them away from all flames and extremely hot areas. Review the Material Safety
Data Sheets.
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GENERAL INSTRUCTIONS
1. The first step is to stop or “capture” the crack - make certain the limit of the crack is determined.
2. At the end of the crack, drill a hole suitable for the installation of an A-200 or A-235 plug.
3. Retest the area to see if the crack runs beyond the hole.
4. Repeat this process until the crack does not run beyond the hole.
Marked Crack Drill Holes for Plugs “Capture” the Crack Cut Off Plugs Peen Plugs
NOTE: The particular technique or method used in repairing the crack varies depending on the location and
accessibility of the crack, thickness of the metal, etc. Experience will develop the most suitable technique for
the operator to use.
This manual will describe some of the most commonly used techniques which will point the way for an operator
to develop his best approach to repairing cracks.
Whatever technique is used, one of the most important parts of the repair process is the peening of the tops
of the plugs after they have been installed and cut off down near the surface of the head or block.
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TECHNIQUE ONE
Installing tapered plugs along the line of the crack in areas of the casting that are subject to high
pressure and temperatures.
One of the best examples of this type of crack is in the valve seat area of the head. In this instance, the plugs
are installed at angles to the casting surface, not perpendicular to the surface. In addition, they are installed
in an overlapping fashion.
1. A plug hole is drilled, reamed and tapped and the plug is fully torqued into place.
2. Cut off the excess part of the plug before the next hole is started. This permits locating the next plug so it
will overlap the preceding plug at the surface and below the surface.
3. Here, where the metal is thick, after drilling, the hole needs to be taper reamed before tapping. This helps
give the tapered tap a reasonable life.
Drill & Tap for Plugs “Capture” the Crack Continue to Fill in with Plugs
(Plugs at each end)
Cut Off and Peen the Plugs Remove Excess Plug Material Refinish Surface like New
4. Cut off the installed plugs (with a small coping or other saw) and peen the tops of each plug
NOTE: The peening process is extremely important. It helps close the threads at the surface of the
casting.
When peening, always peen away from the center of the plug. In the peening process, the position control of
the air hammer is most important. It provides the necessary control over the direction of the ends of the
peening tools.
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TECHNIQUE TWO
Repairing cracks in readily accessible areas of a casting not subject to high pressure and high
temperature, where the metal is relatively thin.
Here, the object is to close the crack with either a series of plugs down the line of the crack or alternate plugs
on opposite sides of the crack, supplemented with a thorough peening of the crack itself.
1. After the crack is carefully outlined, drill and tap holes along the line of the crack about 1/4” to 1/2” apart.
NOTE: Where the material is less than 1/4” thick, it is not necessary to taper ream before taper tapping it.
3. Torque the plugs in concurrently so that none of them will be loosened as other plugs are torqued in.
4. Cut the plugs off about 1/16” above the surface and peen them, always peening from the center of the plug
outwardly toward the thread in the plug.
5. Peen the crack itself, peening inwardly toward the center of the crack.
1 – Drill & Tap 2 – “Capture” 3 – Fill with 4 – Cut Off & 5 – Resurface
Crack Plugs Peen Plugs
Alternately, the plug holes can be drilled and tapped in a lacing fashion on opposite sides of the crack. Torque
the plugs in concurrently and then cut them off. Peen the plugs and the crack in the same manner as above.
This process, in addition to closing the crack with additional metal and with peening the crack, develops a
resistant elasticity in the metal which helps keep the crack closed.
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GENERAL INFORMATION
The examples described in this manual are crack repair techniques intended only to illustrate various
approaches to the process of closing a crack in a casting. They can serve as guides in the process of repairing
many different types of cracks in many different types of castings - industrial as well as engine castings.
The most important factors in closing the crack are the adding of metal by torquing in the tapered, threaded
plugs and the moving of the metal through the peening process.
NOTE: A tapered tap is cutting the full length of the tap, so if the metal is very thick, the hole must be first
reamed with a tapered reamer if the tap is to have a reasonable life.
Even when the hole is reamed with a tapered reamer, it is necessary to use the proper amount of downward
pressure with the tapered tap. For certain larger taps used in repairing and replacing the injector seat areas
in heavy duty diesel engine heads, Irontite has developed lead screw nuts and arbors. To apply the lead screw
principle, give just the right amount of downward pressure on the tap.
NOTE: A good tapping fluid should be used at all times with the tapered tap. Irontite recommends TAP-O
tapping compound. TAP-o does not contain oil or carbon tetrachloride.
Irontite tapered plugs and tapered taps are designed so there will be a tight thread-to-thread fit when the plugs
are torqued into position. When torqueing in the plug, as an added assurance of a leak-proof fit, dip the plug
in Irontite’s Ceramic Seal just before torqueing it in. This will help close any porosity that may be present in
the threaded hole of the casting. Ceramic Seal is recommended because, being fluid it will spread evenly on
the threaded plug as it is torqued in.
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NOTE: When using Irontite Ceramic Seal, it is MANDATORY that the cooling system be cleaned first to make
certain that any anti-freeze or coolant is flushed out and the system is clean. Ceramic Seal IS NOT
COMPATIBLE WITH ANTI-FREEZE OR COOLANT. Combining them in the cooling system will clog the
cooling system.
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Magnetic powder
DESCRIPTION PART #
WHITE
1 lb. Can 400-1220-16
5 lb. Can 400-1220-80
10 lb. Can 400-1221-60
25 lb. Can 400-1224-00
GOLD
1 lb. Can 400-1225-16
5 lb. Can 400-1225-80
10 lb. Can 400-1226-60
25 lb. Can 400-1229-00
GREY
1 lb. Can 400-1230-16
5 lb. Can 400-1230-80
10 lb. Can 400-1231-60
25 lb. Can 400-1234-00
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Extension Drills
DESCRIPTION Plug Type PART #
11/16 HSS Extension Drill A-200 407-5132-00
16/64 HSS Extension Drill A-235 407-5132-35
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Ceramic Seal
DESCRIPTION Size PART #
Ceramic Seal Pint 468-9120-16
Ceramic Seal Gallon 468-9121-28
Ceramic Seal 5 Gallon 468-9126-40
Thoro Flush
DESCRIPTION Size PART #
Thoro Flush Pint 468-9110-16
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