Rottler HP 7A - Using Vitrified Abrasives

Section 5 Operating Instructions HP7A Manual
www.rottlermfg.com
5-6
Note:
When looking at actual honing time only, the two step process is 5.5 minutes faster than the single step
process. Because the operator must change abrasives in the two-step process 1-2 minutes should be
added for two abrasive changes. Considering the operator must position the machine in each cylinder
two times for the two-step process, the time difference between the two methods is slight. The single step
process allows for more operator uninterrupted free time.
The single step process would allow the operator to easily run two machines at one time or perform work
other than honing.
The two step process becomes more effective as the ending surface nish requirement becomes
smoother. If a 12 - 16 Ra nish was required, the honing time for a single step process would become
approximately 24 minutes and the honing time for the two-step process would remain near 10.5 minutes.
The two step process becomes more productive when more than .003 of material must be removed.
The above calculations should be made to determine the best method for the customer’s particular
requirements. Actual times will vary depending on the engine block material, stock removal required, and
the desired accuracy. The purpose of the above comparison help the user understand different methods
may be used to obtain the same result and that there is a signicant difference in potential productivity
when comparing the different methods.
Using Vitrified Abrasives
Abrasive grades are available for most any nish you want to achieve. Two or three bond hardnesses are
available with most grits. The right bond hardness will break down gradually depending on the grit used.
Too soft a bond will lose abrasive excessively. Too hard a bond will chatter and start glazing the bore,
with rapid heating and poor stock removal.
Finer grit stones generally break down much faster than coarse grit does. They must break down quickly
to prevent the stone from loading or glazing. Bond hardness will act differently with different cutting oils.
Rottler abrasives were designed to be used with Rottler honing oils or equivalent. In general, Rottler
honing oil is of low Sulfur content. Using other honing oils may have an adverse effect on the abrasive
performance. Faster spindle rotation and light pressures will make abrasive act harder. Faster stroke
speed and heavy pressures will make abrasive act softer.
Abrasive should wear relatively evenly and parallel to the shim support. If you encounter uneven abrasive
wear, the cause may be damaged universal drive joint, unmatched stones, or misalignment of hone drive
with cylinder bore.
Standard Vitried abrasives can not be used in synthetic or water base coolants.
Generally, lighter honing pressures are required when using vitried stones compared with diamond
stones. The ner the grit the lighter the load should be as follows.
80 Grit 40 – 60%
180 Grit 40 – 60%
220 Grit 30 – 50%
320 Grit 20 – 40%
400 Grit 10 – 30%
600 Grit 05 – 25%
See H-Series Optional Equipment Catalog for list of available abrasives.