Acceptable vs Non-Acceptable Wear of Retaining Caps

Hypertherm Retaining Caps - HPR

The plasma cutting torch has many CNC consumables and to ensure that the plasma cutter consistently produces high-quality cuts, all the consumables must be maintained and in a good condition. The plasma torch contains 2 sets of retaining caps – inner and outer.

Inner Retaining Cap

The inner retaining cap helps to hold the swirl ring and the nozzle in place when the coolant flow is directed to the outer part of the nozzle. There is a composite ring that encompasses the inner caps that is meant to be placed on the shield in a position concentric to the orifice of the nozzle and direct the secondary gas towards the shield.

The size of the ring depends on the amperage of the plasma cutter and despite the size of the ring, you must inspect it closely and ensure that it is completely round and the surface of the ring is smooth. You must also make sure to check if the ring is not cracked or burned. Also ensure that the holes under the top edge of the ring are not clogged and are free of grease, metal spatter and other kinds of debris. Sometimes, inner caps have bleed holes also on the base. And, if the cap has holes at the base, make sure you check these too.

Outer Retaining Cap

The outer retaining cap essentially keeps the shield in place on top of the inner cap and also directs the shield gas towards the shield. There is a contact tab present on the outer cap that is used sometimes on THCs as an electrical contact to the work plate.

You must inspect the outer retaining cap carefully and check the following: The top opening of the cap should be completely round without any arc marks or nicks. The threads at the base of the outer cap must be clean and should not be worn out.

The life of the outer retaining cap can be prolonged by cleaning it with a rough cleaning pad, which removes any spatter. Also, use a water-based anti-spatter spray on the cap.

Taking very good care and maintaining both the inner and outer retaining caps of your plasma torch can ensure that they last for a long time. And, the change-out ratio of these caps to the electrode is typically 100:1, which essentially means that you will require changing the inner or outer retaining cap only once when the electrode has undergone 100 changes. However, the secret to that is to keep both the inner and outer retaining caps extremely clean.

Escco sell a range of CNC consumables including retaining caps from manufacturers including Lincoln and Hypertherm. Feel free to contact us if you require any advice on any of our engineering consumable products.

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