Enlargement of the raw blockEnlargement of the raw block

The model should be a little bit bigger than the origin data

to avoid burr at the edge of the raw material

Limit of the raw blockLimit of the raw block

For roughing sometimes it is possible to limit the raw block

RestmaterialstrategyRestmaterialstrategy

Use restmaterial strategies for abbreviation of milling times

the area should overlap enough to the already milled surface

Choice of tool radiusChoice of tool radius

To avoid vibrations use a significant smaller tool radius

than the contour radius

Choice of tool diameterChoice of tool diameter

Do not take the nominal diameter in your CAM-System

Calculate with the real diameter, that is determined by

measurements on the machine or experience figures

Consider the tool holder and the clamping system that has

influence on the working diameter

Approach moves in roughing strategiesApproach moves in roughing strategies

To approach into the material use an angled ramp

steel 4° angled ramps max, aluminium and copper 10° angled

ramps max

Approach moves in roughing strategiesApproach moves in roughing strategies

Approach outside, if possible

Rounding of cutter movesRounding of cutter moves

Roundings decrease the strain of the tool

Avoid tool overloadAvoid tool overload

Use different possibilities to reduce tool overload

Trochoid moves reduce the tool overload

Decrease of tool strainDecrease of tool strain

Insert one move before the last one to reduce the strain

that can occur in the last move with its corners

Different ThicknessDifferent Thickness

Use different values for axial and radial thickness

effective programming possible by making less programs

Safety heightSafety height

Set the Safety height to large values

Low safety heights do not save much time

Low safety heights increase collision risk in special cases

Safety HeightSafety Height

Roundings of retract moves decrease the milling time

because there are often a lot safety moves

if all safety points of view are considered then lower safety

heights are allowed

Approach movesApproach moves

Leads on surfaces are visible in most cases

better start at corners or inconspicuous areas

Approach movesApproach moves

At steep area strategies horizontal and tangential arcs are

recommended

Take arcs as big as possible

Approach movesApproach moves

At flat area strategies vertical and tangential arcs are

recommended

Take arcs as big as possible

Corner roundingsCorner roundings

Rounding in the corners avoid vibrations of the tool

a bad grinded tool enhances these vibrations

D x 0.05 are usual values for the radiuses

Corner roundingsCorner roundings

Rounding in the corners avoid vibrations of the tool

D x 0.05 are usual values for the radiuses

Corner roundingsCorner roundings

If the CAM System does not offer the possibility to insert

roundings into the cutter paths you can insert rounded

surfaces an delete them afterwards

Start areaStart area

The start area should not be in problem areas

better work towards corners

Start areaStart area

Start in the middle of the surfaces if approaching outside is

impossible

only small areas are in full cut

Polygonic top surfacePolygonic top surface

A circular hole in a top surface is in each CAD/CAM-System a polygon

The quality depends on the CAD tolerance that is used for the modeling

process

The elements of the polygon run inside the origin circle, the polygon is smaller

than the circle at several parts of the circle

The tool can not cut the origin circle The tool can not cut the origin circle

contour

If the modelling tolerance was too big

this is visible on steep surfaces

Use very small modelling tolerances

for this operation (0.001 or less)

Polygonic top surfacePolygonic top surface

Program example

Milling of opposite surfacesMilling of opposite surfaces

Default settings of CAM Systems often mill one surface

first, then the other. That causes tool strain and damage

because the tool dives under the material of the opposite

side

mill narrow slots in layers to cut the complete material from

top to bottomtop to bottom

Point distribution depends on surface anglePoint distribution depends on surface angle

Point distribution alter and move distances increase

Milling of steep areasMilling of steep areas

Mill only the real steep areas, otherwise:

The distances of the moves become too big

The point distribution becomes non-uniform

The milling time increases

Milling of flat surfacesMilling of flat surfaces

Mill only the real flat areas, otherwise:

The distances of the moves become too big

The point distribution becomes non-uniform

The milling time increases

Combination of different strategiesCombination of different strategies

Overlap flat area programs and steep area programs 20°-30° to get soft

program changeover

Use different thickness to makes the border of the different programs invisible

To achieve, use different thicknesses in CAM, different tool diameter, or move

programs in the command file

Combination of different strategiesCombination of different strategies

Usual way to mill: steep area before flat area

if steep area >85° and flat area <5°the opposite can be

better. First finish the bottom with distance to the wall

Then mill the wall from top to

bottom.

The tool gets no overstrainingThe tool gets no overstraining

Milling of areas with objects insideMilling of areas with objects inside

If rastering significant flat surfaces, the CAM Systems order the

moves depending on limitting objects inside these surfaces

The result is a restart at areas where the machine temporarily

ends to cut long time ago.

The restart move is visible, consolidated by the tool that is

wear out in meanwhilewear out in meanwhile

better accept a lot of retract moves to have a uniform surface

Collision checkCollision check

Determine the most stable tool with the collision check

If nessecary divide the program into several programs,

one for a short tool, one or more for longer tools

length/diameter ratio of 5 has enough stability, beyond this

ratio the stability becomes worse, more than 8 is not

process safe process safe

Collision checkCollision check

For milling very steep areas the tool must be grinded free

to avoid tool vibrations and contour damage

The Choice of the right strategyThe Choice of the right strategy

Choose the strategies depending on the kind of surfaces

that must be milled

steep areas: Z-level flat areas: Raster, Spiral,

corner finishing: equidistant, stitching, projection

Specpath (Ver 3.21)Specpath (Ver 3.21)

For optimizing spiral cutterpaths the specpath command

offers the possibility to raise the first paths

origin cutterpath must have only spiral contour, no circles,

no several paths

different options and switches define the type of raising

too see what happens use the RMSCut-Simulationtoo see what happens use the RMSCut-Simulation