pass-fail. In our educational system, a student who
answers 99 percent of the questions correctly will get
straight A's. By contrast, an MR may manufacture 99
percent of a part perfectly, but the part ends up in the
scrap bin because of the 1 percent done improperly. The
part must be redone and the costs are additional time,
effort, money, and embarrassment to the machinist.
Quality assurance is used to lay out procedures in
which we assemble and disassemble components and
repair their parts. All MRs must be familiar with QA
since it is something they will use every day on the job.
Figure 13-1.--Part made in a machine shop.
Refer to your type commander's quality assurance
manual, w h i c h is developed according to
SECNAVINST 4855.1, for information on the quality
assurance program. Engineering Administration,
Once you have the job planned, be sure all
NAVEDTRA 12147, also contains a chapter on QA that
documentation is properly recorded from the start of the
is condensed and easily understood.
job until the finish.
PLANNED MAINTENANCE SYSTEM
Maintenance is one of the most important jobs you
The Navy supply system usually provides
will do in the Navy. The degree of accuracy to which
replacement parts for most equipment, but occasionally
you can machine a part is often directly related to the
you will need to make parts such as shafts and gears.
condition of the machine tools you are using. If
preventive maintenance is not done properly, or not
A major portion of the repair work done in
done at all, your equipment may be put out of
shipboard machine shops involves machining worn or
commission until it can be repaired.
damaged parts so that they can be placed back in service.
Preventive maintenance includes actions to prevent
For example, you will machine the sealing surfaces of
equipment from failing, such as taking oil samples,
leaking valves and pumps, remove broken studs, and
changing the oil, greasing, cleaning or replacing filters,
repair bent or damaged shafts. Repair work is usually
or simply cleaning each machine before and after its
more difficult than manufacturing work because of
alignment problems in the machining operation.
Information on the planned maintenance system is
found in Ships' Maintenance and Material Manage-
ment (3-M) Manual, OPNAVINST 4790.4.
If you work in a machine shop, some of your
common jobs will be to manufacture, straighten, and
stub shafts. We will discuss them in the following
Occasionally you may be fortunate enough to have
a TRS (technical repair standard) to give you
Manufacturing a New Shaft
step-by-step instructions for a job. Unfortunately there
are very few TRSs for machine shop work. You
normally have to plan the steps for each job.
of operations by which a shaft might be made in a
To start with, you will need to research technical
machine shop. The manufacturer's technical manual for
publications or blueprints for job specifications. If a job
the equipment that contains the shaft will normally have
is as-per-sample, you may need to draw your own
blueprint. Decide which machines are required to make
the part and calculate all necessary dimensions. Choose
Select and cut a piece of round stock at least
the most logical sequence of machining operations so
1/16 inch larger in diameter and 1/8 inch longer than the
that the part is machined in a minimum of setups. Be
shaft. Face and center drill each end of the stock. In
sure the correct material is on hand for the job.