My best exit location results were with a paper core with melamine
facing entry product. I tried three different vendors of alum clad entry
and my results were all over the map. Pure alum results were middle of
the pack. I think results are greatly affected by material grade,
thickness, and vendor process variation. "Hard" is not always bad if
the drill can quickly pierce the melamine facing.
Mark R Ford wrote:
>
> Gentlemen,
>
> Drill wander is the byproduct of one of the following factors:
>
> 1. If you are using an extremely "hard" entry material, ie.
> phenolic
> or melamine, the drill can have a tendency to "skate" on the entry prior
> to
> penetration. This will usually cause excessive drill wander and have
> detrimental
> effects on front to back registration for obvious reasons. If you are
> using
> on of these types of entries, try using LCOA EO+ ( an aluminum clad
> cellulose
> core material) or 7 to 8 mil virgin aluminum foil. The EO+ seems to work
> better
> in suppressing drill wander.
>
> 2. If the flute to diameter ratio is too great ( greater than
> 20:1) than this
> can be a contributor to drill wander. The first thing that you should do
> is call
> your drill vender and have them analyze your situation. Many times they
> can
> offer a tool that better fits you particular application. If they don
> have any
> standard product for you to test, see if they will design a tool that
> better fits your needs. If your drill vender cannot build a
> special...get a new drill vender!!!
>
> 3. If the spindle runout is excessive, it can have an effect on
> drill wander.
> Contact your drill machine supplier and find out what their
> specifications are
> for spindle runout ( most are between .0002" to .0005"). Try to perform
> a runout check at least once per week. A fairly good barometer, should any spindle have excessive runout, is drill breakage, however, depending
> on the diameter of the tool you
> are using, this is not always the case.
>
> 4. Lastly, tool geometry and carbide selection can have an effect
> on
> drill wander. Designing cutting tools is a constant game of trade-offs.
> If you want
> a stronger tool that will have better resistance to breakage and
> deflection, the trade-
> off is usually a decline in hole quality. if you want a tool that will
> produce excellent
> hole quality, you can bet that you will have more breakage, increased
> drill wander,
> and reduced stack heights. The task of the drill room process engineer
> is to find
> the happy medium that will share the best of both worlds, however, it
> behooves
> the engineer to involve their machine and tool suppliers to assist in
> this endeavor.
>
> I wish you success in this project.
>
> Regards,
>
> Mark R. Ford, North East Application Engineer - Megatool
>
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