Metalocking and Metal Stitching

Metal stitching or metalocking is a simple but effective method of repairing cracks in cast metals without the need of welding.

Metal Stitching Repair Process

The illustration of the Metalock Repair System (Metalocking), shown below, is a basic repair to a flat surface. Damage to more complex fractures and castings requires the Metalock Engineer to draw on his skills and knowledge in coping with both the difficulties of the component’s shape, its operation and its working environment.

This all has to be completed, often with a minimum downtime, frequently involving 24/7 working.

1. Following the survey, a report is presented to the customer in order to get the go-ahead for the repairs. The component is then positioned, realigned and held firmly in position using clamps and special fixtures.
2. Using the Specialist Metalock Jigs, groups of holes are drilled across the line of fracture to the tool depth of the casting.
3. The holes are then joined by the use of pneumatic chisels to conform to the shape of the Metalock Keys.
4. The Metalock Key is a multi-dumbbell shaped section of a highly ductile alloy that is manufactured in various sizes, these can be cut to any length required, to suit the type of fracture.
5. Individual layers of Keys are inserted in the apertures and peened into a metal-to-metal condition, which becomes almost integral with the parent metal.
6. Holes are then drilled along the line of the fracture, then tapped, and filled with studs, each stud biting into its predecessor, resulting in a pressure-tight join that restores rigidity to the casting.
7. A Metalock stud is an important aspect of the Metalock process, bearing in mind that pressure repairs are often required.
8. The studs are then run down until the heads shear, the remaining rough metal being removed by pneumatic chisels.
9. The whole repair is ground over until smooth
10. Then it’s the final coat of paint

A trusted Technique Used to Repair Machines and Structures

Whilst the tried, tested and unique repair system is a repetitive operation, the application is as varied as the plant and machinery for which it is designed. This extends from ship’s engines to power presses and petro chemical installations to old structures and heritage buildings.

Over 70 years ago the Metalock Engineering Group developed special tools, jigs, fixtures and materials used in this simple but ingenious repair procedure and these tools enable the successful cold repair of all types of machines and in the restoration of heritage structures.

Some of the Advantages of the Metalock Process:

• Dampens and absorbs compression stresses
• Provides a good ‘expansion joint’ for such castings as cylinder liners, diesel heads or any vessels subject to thermal stresses
• Distributes the tension load away from fatigue points
• Maintains alignment and original surfaces, since lack of heat produces no distortion
• The vast majority of repairs can be done in situ, with little or no dismantling saving time and money

The Metalock Engineering Group has an excellent record in performing successful cold cast iron repairs using the cast iron stitching method.

When compared to welding there are many possible problems and using this metal stitching technique to fix cracked components, is the preferred repair solution.