Metal Stitching

Repairing Cast Iron

Cast iron will only crack when it is stressed beyond its tensile strength. This includes all heat-related cracks, freeze cracks, impact and bending loads. Cast iron is a significantly durable metal that will not weaken over time. Still, it will change if exposed to high temperatures over long periods like exhaust manifolds. In-Situ offers a superior on site crack repair process as part of our range of on site machining solutions.

Dangers of Graphitisation

Amorphous carbon expelled from exhaust manifolds is a free, reactive carbon with no crystalline structure. However, when heated for an extended amount of time, the atomic structure is rearranged into a crystalline form typical of solids. This process is called graphitisation. The carbon is changed to graphite, and any welding that requires melting the cast iron becomes very difficult because the filler metal will not bond properly.

Cracked Cast Iron Repair Service

Metal stitching (also known as a cold casting repair) is a method of repairing cracking or fractures in all forms of cast metals, including cast iron stitch repair, without the necessity to weld. Cast iron stitching is one of our most popular services and an excellent alternative to conventional repair methods, as cast iron is one of the most challenging metals to repair by welding. This challenge is only made harder when trying to repair cast iron in-situ, which is why you must choose trained engineers who are experienced in conducting this operation.

The metal stitching conducted by our expert engineers allows us to permanently repair a crack or replace a damaged casting section without welding. Instead, the crack or damaged area is either removed and replaced with a new section (or stitched) with specially designed stitching pins that we install.

These are inserted along the split line after a series of drilled and tapped holes are inserted, drawing the sides of the crack together. This results in a continuous row of interlocking stitching pins to create a robust, pressure-tight repair. Next, to add additional strength to the casting and repair, we install high tensile locks across the joint line of the pins by drilling a precision hole pattern with special drill fixtures. After the hole pattern is created, the locks are driven in, exerting a pulling force at 90 degrees to the crack to provide additional strength.

Our engineers are also experienced in various machining solutions such as main bearing journal repair and line boring services. Below are images sharing our teams’ success in repairing cast iron with metal stitching. Contact us with the enquiry form below if you have any questions about our metal stitching or other services.