Relapping the heads of your machines is a routine maintenance procedure that can drastically extend their life. Typically, you should relap the heads when they reach 50% life. But what should you use to do this? This article explains how to relap a machine head. In the meantime, you can read about other relapping methods, such as using 3M lapping film, or ordinary wet/dry abrasive paper.
HF droop method
The HF droop method for relapping tape heads is a simple procedure. The tape head is ground down and shaped to restore its proper shape. This procedure is only effective on a single head, and should only be performed by trained technicians. Incorrectly relapped heads can cause many problems. Incorrectly relapped heads may not perform as well as new heads.
The HF droop method for relapped tape heads can greatly reduce the tension and wear of a machine’s tape head. It can reduce the tension and wear of the tape while minimising the overall spool weight. The droop method is not effective on all tape heads, but a 2″ head is generally the easiest to lap. If you cannot find a HF droop kit, it is possible to use an ordinary abrasive paper to relap a head.
Before retaping, make sure that the azimuth of the head is aligned with that of the playback head. The two heads must be aligned, and the azimuth of the playback head should match the record head’s. Using externally prepared test tape to align the head is an excellent method of ensuring that the head has the right azimuth alignment.
A similar technique is used for relacing a head’s frequency response. The difference between the HF droop method is that the abrasive grit is more precise than that used for 10kHz biasing. Moreover, it allows a tape head to reveal the presence of any aging components. This technique works well on recording low frequency signals and is also efficient.
3M lapping film
When relapping tape heads, it is a good idea to use high-quality lapping film. 3M(tm) Lapping Film 263X Rolls are a high-quality polyester film with aluminum oxide mineral coated on the surface. They are available in seven different grades to meet the needs of a wide range of applications. Those who use 3M lapping films often use them for optical fibre optic connectors.
The lapping film’s cutting capability decreases rapidly when compared to hard materials, such as tape heads. The lapping film can be replaced with a finer-grit abrasive after four passes to remove scratches. This method will also improve the overall surface quality of the finished magnetic head. The lapping film will also reduce recession and rolloff on critical head elements located at the air bearing surface.
The use of lapping film reduces the amount of time necessary to flat-lap a fibre-optic connector. This lapping film is composed of aluminium oxide minerals, which are both hard-wearing and strong. Furthermore, this film is used to relap media-heads. As a result, it is the perfect solution to the problem of relapping tape heads. This film is ideal for finishing media-heads, reducing the time needed for flat-lapping them.
A relapped tape head should have a mirrored appearance. When new, the tape head’s oxide surface is in intimate contact with the head pole, so even the slightest separation will reduce the recording and playback efficiency. A slight separation may occur due to uneven wear of the head, insufficient tape tension, or oxide deposits on the head face. The most common head manufacturer in the world, Nortronics, recently released a magnetic head relapping kit called Handylap.
A DIY relap board can be made out of pinewood. The board should be approximately 65cm long, 2 cm thick, and 25 cm wide. Another important component of the lapping board is a piece of plate glass. It should be optically flat, and the edges should be ground to prevent nicks and chips. Make sure the glass is tempered. This product has been proven to be a great asset for many companies.
Ordinary wet/dry abrasive paper
The first step in relapping tape heads is to identify the head type. Glass heads are generally softer than ferrite and will saturate more easily than other types of tape. You can identify a glass head by its gap, which tends to chip away as it wears. Ceramic heads may be more difficult to relap than other types of heads, but they are still possible.
To begin, place a lapping board over a sink with water running. Place a wood dowel at the back of the plate glass. Cut your abrasive paper to fit the size of the glass plate. Dip the abrasive paper in water to make it adhere to the plate glass. After the glass dries, relap the head with a 400-grit abrasive sheet. Once the face material is removed, you’ll notice fine scratches. Use a finer film to polish off the scratches that the 400-grit film left.
JRF lab report
The JRF magnetic head undergoes precision relapping. The magnetic head is ultra-high polished with diamond compounds and vapor spraying technology. This process is designed to maximize the life of recontoured magnetic heads. The procedure involves removing material from the head’s face and gap to the point of deepest wear. The results of this relapping procedure are documented in the JRF lab report.
About The Author
Mindy Vu is a part time shoe model and professional mum. She loves to cook and has been proclaimed the best cook in the world by her friends and family. She adores her pet dog Twinkie, and is happily married to her books.