PM 14 2D Feature Sets

PowerMILL 14. Feature sets /2D machining

Issue PMILL 6.0 191

14. Feature sets / 2D machining

Introduction PowerMILL has a range of 2D strategies, which are specifically applied to vertical, extruded shapes called Features. These are machined independently and as a result are not gouge checked to the surface based CAD model. Features are extruded from internally created Patterns or wireframes imported from a range of different model file formats. When a Feature is created it is displayed as an upper and lower contour linked by vertical lines. An Active Feature is coloured purple while an Inactive Feature is coloured light grey. Unlike a surface based CAD model it is not possible to colour shade a Feature. 1. Features Features are created from 2D geometry, and are individually defined as a Pocket, Slot, Boss or Hole. It is also possible to extract Hole features directly from a Surface or Solid model as well as from Area Clearance strategies when using the Drilling option for Lead In Moves. 2. Area Clearance (2D machining strategies) On completion of Feature creation, the 2D Area Clearance strategy menu is used to create all the 2D machining including roughing, semi finishing, and finishing strategies. 3. Drilling. Drilling options can only be applied to Hole Features. Types of cycle supported include Standard drilling, Boring, Helical milling, and Tapping.

Features There are six different types of Feature which respond very specifically to the 2D machining options:- 1. Pocket, defines the area inside a profile, therefore the tool will only machine the inside

the Feature. 2. Boss, is an upstand. The tool will only machine around the outside of the Feature. 3. Slot, is curve based defining the track of the tool (with or without cutter compensation). 4. Hole, this is specifically used with Drilling strategies and is defined from points, circles,

curves, or directly from CAD model data. 5. Circular Pocket - a circular pocket is defined from points, circles or curves. 6. Circular Boss - a circular boss is defined from points, circles or curves. Stacked 2D data containing pairs of circles/curves or cylindrical surface data can be imported into PowerMILL to be directly defined as Hole features, thereby removing the need to manually input dimensions (eliminating a possible source of human error).

14. Feature sets /2D machining PowerMILL

192 Issue PMILL 6.0

Creating Features from Wireframe.

Drilling

Feature generation Delete All and Reset Forms. Import the model PM_holes.dgk from Examples.

Create a new Feature Set from the PowerMILL

explorer.


Issue PMILL 6.0 193

When selecting Create Feature Set from the Feature right click menu the Feature Form is automatically diaplyed.

Input Name root as 1. Select the option for Type as Hole. Input Values for Define top by as 0 and

Define bottom by as 25. Select the option for Use as Curves

Select all the wireframe Circles from the Graphic Window. Apply and Close. A Feature is created over each of the circles at its correct diameter value. Z 0 at the top and Z25 at the bottom.


194 Issue PMILL 6.0

Define a Block to the exact Feature size by selecting Type - Feature before Calculating.

Expand in X - Y only by 10 (Lock the Min Z - Max Z values first). From the Toolpath strategies form, select the Drilling tab Select Drilling. Define a Diameter 10 Drill Click on the Select button to bring up the Feature selection form which is

shown on the next page.


Issue PMILL 6.0 195

All the Hole sizes in the Feature Set are shown in the left hand box of the form. Select the Dia 10 holes. Click on the Transfer button to move the

Dia 10 holes to the selection area. Click on the Select button to highlight the chosen Hole Features in the

graphics area and Press Close. Select Deep Drill from

the Cycle Type section. Set Define Top By to

Hole Top. Enter Clearance 3 and

Peck Depth 5. Click on Ordering and

select Shortest path. Apply and Close the

form. A Drilling toolpath is created in the Explorer area.

Right click on this toolpath and select Settings to bring up the Drilling

form again. Select Edit Copy.


196 Issue PMILL 6.0

Define a Diameter 16 Drill and create a Drilling strategy for the Diameter 18 Hole Features in the same way as used previously for the Diameter 10 Holes.

PowerMILL displays this message just as a check that the user has not unintentionally selected an incorrect drill size. The selected Holes will still be drilled.

Define a Diameter 25 Drill and Drill the Diameter 40 Feature. This 25 drill is used to create a Pilot hole. The next operation will be to use a 30 Endmill to Helically machine the Hole to size. Define a 30 diameter Endmill. Select the diameter 40 hole Select Helical from the Cycle Type section. In the Pitch area enter 1 (which will be the pitch of the helix) and then

Apply and close the form.

Exercise Create a Pattern, from a Sketch, to add 2 additional Diameter 6 Holes,

30mm each side of the Diameter 40 Hole, with 3 Degrees of Draft. Define suitable tools to Drill and Machine the two new Holes.


Issue PMILL 6.0 197

Pocket, Boss and Slot Features For this exercise the 2D drawing shown below will be used. Three Features will be generated and used later on for 2D machining. Refer to this dimension drawing when filling in values.

Delete All and Reset forms Import the model 2d_Wizard_Example.dgk from the Powermill_data

Models folder.


198 Issue PMILL 6.0

A slot, pocket and boss feature need to be created and machined. The 2.5D Machining Wizard guides the user through the process of creating 2.5D toolpaths from wireframe or surface topology.

Select Toolpath strategies . Select the 2.5D Area clearance tab

Select the 2D Machining Wizard. Create a New feature with the name Example and select Next to

advance to the next stage of the Wizard.


Issue PMILL 6.0 199

Select the pocket

wireframe with the left mouse button so it is yellow.

Define the top of the feature by an Absolute value of 0, bottom by an

Absolute value of 25 and a Draft Angle of 5. Set the Feature type as Pocket. A pocket feature is created and displayed in the feature list. De-select the pocket. Select the inner profile

and using the values shown, generate a Boss Feature.


200 Issue PMILL 6.0

A boss feature is created and displayed in the feature list.

The Wizard also contains an option to delete selected features. Select the Centre Line

wireframe and using the values shown, define a Slot Feature.

Undraw all wireframe to view the created features.


Issue PMILL 6.0 201

Select Next to advance the wizard. This page of the wizard allows the user to select the required features for machining Select the Slot feature followed by Next. This page of the wizard allows the user to Define basic parameters for the toolpath. Select the Block icon, enter the values below and Accept the form.


202 Issue PMILL 6.0

Set the Start Point as Block centre safe z. Set Rapid Move Heights as Safe 5, Start 2. Select Next to advance the wizard. This page of the wizard allows the user to select a machining strategy. Note: 2.5D Area Clearance is the only type of strategy that can be used to machine Features. Select the Profile AreaClear Feature Set strategy followed by Create.


Issue PMILL 6.0 203

Do NOT close the Machining Wzard.

Define a 10 diameter

EndMill. Set Thickness 0. Set Stepdown to 2 Set Cut Direction to

Climb. Set Slot Cutting to

Centreline. Apply the form.

A toolpath is generated through the slot centre.

Make a Copy of the Toolpath and modify the Slot Cutting to Keep Left.


204 Issue PMILL 6.0

A toolpath is generated to the left of the slot centre.

Make a Copy of the Toolpath and modify the Slot Cutting to Keep Right.

A toolpath is generated to the right of the slot centre. Select Back on the machining wizard to return to the Select Features

Page. Select the Pocket and Boss feature followed by Next.


Issue PMILL 6.0 205

Select the outside edge of the 2D data and select Boundaries in the

explorer followed by Create Boundary - User Defined.

Create a User defined Boundary from Model

and Accept the Boundary form. This Boundary will be used to create the Block. Select the Block icon, from the machining wizard. Define the Block by Boundary , Set the

Min Z to 30 and Accept the Block form.


206 Issue PMILL 6.0

Select Next to advance the wizard. Select the Offset AreaClear Feature Set strategy followed by Create. Do NOT close the Machining Wizard.


Issue PMILL 6.0 207

Define a Tipped Radius

tool, diameter 12, rad 3 Lead in to Ramping. Set Thickness 0. Set Stepdown to 5 Set Cut Direction to

Climb. Tick Final Profile Pass

and enter an Allowance of 1.0 with Last Z.

Apply the form and

Cancel.

Run all toolpaths in Viewmill. It will be necessary to define a suitable tool to apply the draft angle to the pocket walls.


208 Issue PMILL 6.0

Create a Tapered Spherical tool using the values as shown below. Select the Profile AreaClear Feature Set strategy, from the Machining

Wizards Toolpath Creation page, followed by Create.

Fill in the form as shown

using a Manual Stepdown value of 25.

Apply and Cancel the

form.


Issue PMILL 6.0 209

Apply suitable leads and links to the toolpath and simulate in viewmill.

Creating Features from Model holes As well as being able to use imported 2D geometry, 3D surface and solid models can have hole features defined automatically from Blind or Through holes in the 3D model. Delete All and Reset forms and from File > Examples, Import the model

corner_bowl.dgk. Make sure the Block is not defined at this stage. If it is the Hole features will not all be created the correct way round.


210 Issue PMILL 6.0

Select the whole model. Right click over Feature Sets and

select Recognise Holes in Model. Calculate a Block based on the min/max limits of the model. Undraw the model A Feature is created over each of the holes in the model (including the counter-bores). Define suitable tools, then drill and counter bore these holes

Hole Capping Hole Features can be used as the basis for capping holes in the model. If the intersection of the hole and the top face is non-planar, PowerMILL will try and cap the hole with a curved surface, matching the tangency of the surrounding surface. If it is not possible to create Hole features because the holes are not exact, circular sections then it will be necessary to follow the capping procedure in the Edit Boundaries chapter. In The exercise below we will go through the process of capping Hole Features created from a model.


Issue PMILL 6.0 211

Exercise Delete All and Reset Forms. Import the model Block_with_holes.dgk from PowerMILL_Data. Calculate a Block based on the min/max limits of the model. Select the whole model by holding down the left hand mouse button and

dragging a box over it. Next Hole Features will be created from the model. Select Recognise Holes in Model.

Feature Set, 1 will be created containing 9 Hole features extracted from the model.


212 Issue PMILL 6.0

In this case the holes will be created upside down so they need to be reversed. Right click on Feature Set, 1 and select Edit > Reverse Holes. Finally, select the top surface then right click over feature set 1 and select

the Cap Holes option. The Cap surfaces will be generated and new model called Capping Surfaces created along with a new level of the same name. Expand Levels by clicking on the + symbol Click the light bulb to un-draw the level. Also Click the Feature Set light bulb off to un-draw the features.

The capping surfaces may be facing the wrong direction.


Issue PMILL 6.0 213

Select all the cap surfaces, right click on them and pick Reverse Selected. 99 Click the light bulb to draw the Block with holes level back on.

Exercise:- Load in the 5axis_with_holes.dgk file from the examples directory and

cap all the holes. Creating Features from 3DModels. Delete All and Reset Forms. Import the model 2DExample.dgk from Examples. The model contains a combination of Pockets, bosses and slots.


214 Issue PMILL 6.0

Calculate a Block based on the min/max limits of the model. Select the Two surfaces shown.

Select Toolpath strategies . Select the 2.5D Area clearance tab. Select the 2D Machining Wizard. Create a New feature with the name Example2 and select Next to

advance to the next stage of the Wizard. Input the values shown and create a Pocket feature. The Wizard creates two pockets using the supplied data and also identifies the three Bosses based on the trimming of the surfaces used.


Issue PMILL 6.0 215

Select the three Bosses and apply a Draft Angle of 3 Degrees. Select Next to advance the Wizard.

Do NOT select any features for

machining. This way all features will be machined.

Select Next

Reset Rapid Move Heights and Start Point. Select Next to advance the Wizard. Select the Offset AreaClear Feature Set strategy followed by Create.


EndMill. Lead in move Ramping. Set Thickness 1. Set Stepdown to 4 Set Cut Direction to Climb. Apply and Cancel the form.


216 Issue PMILL 6.0

A toolpath should be created similar to the one below. Return to the Feature selection stage of the Wizard by choosing the

Select Features option. Select the pocket that does not contain any Bosses. Advance to the Create Toolpths stage of the Wizard.


Issue PMILL 6.0 217

Select the Profile AreaClear Feature Set strategy followed by Create. Rename the toolpath Pocket Finish.

Fill in the form as shown

using a Manual Stepdown, Defined by Flat.

Apply and Cancel the form. Apply a Lead in/out move to the toolpath Horizontal Arc, Angle 90,

Radius 5. Save the Project as 2Dtest.


218 Issue PMILL 6.0

Return to the Start of the Wizard and create a New Feature Set with the

name Slot.

Select the Create Workplane icon. Rename the workplane Slot Select Align to Pick and choose the bottom surface of the slot.

A workplane will be generated called Slot that is automatically aligned to the selected surface.


Issue PMILL 6.0 219

Select a view along the X-axis. With the bottom surface of the slot still highlighted, Select Next to advance

the Wizard. Input the values shown and create a Slot feature.

The feature is created displaying top and bottom grab handles that allow the user to dynamically define the top and bottom of the feature

Grab the top handle and drag the Ztop

value to approx 30.0mm.


220 Issue PMILL 6.0

Advance the Wizard to the Parameters stage. Define the Block using the Min/Max Limits of the Feature as shown in the

form. Reset SafeZ Heights. Advance to the next stage of the Wizard. Select the Profile AreaClear Feature Set strategy followed by Create.


EndMill. Lead in move Plunge. Set Thickness 0. Set Stepdown to 5 Set Cut Direction to

Climb. Slot Cutting Keep Left. Apply and Cancel the

form.


Issue PMILL 6.0 221

The Slot is Machined.

Area Clearance Cutter Compensation. There is an additional option for applying Cutter Compensation to a toolpath available from the Expert area of the Area Clearance dialog. Activate Toolpath Pocket Finish. Select the Settings of the toolpath and make a Copy. Select the option to toggle the Expert Area Clearnce form.

Automatic is the default setting when creating a toolpath. PowerMILL compensates for the entire tool radius, and in doing so assumes the tool used is an accurate tool size, meaning the user is not required to define compensation at the machine tool. Set the compensation type to Off and

Apply the toolpath.


222 Issue PMILL 6.0

With Off selected PowerMILL will not compensate for the radius of the tool. In this instance it is required to define the tool radius at the machine tool. This process is often referred to as Part Edge Programming but is of limited value as most machine tools will not accurately represent the contour in concave corners, or when an arc exists that is less than the tool radius. Select the Settings of the toolpath and make a Copy. Set the compensation type to Protected and Apply the toolpath.

With Protected selected PowerMILL compensates for the nominal tool radius and the machine tool compensates for any difference. This is often referred to as Wear Compensation. It corrects for the limitations of the Off option by ensuring that, in concave corners, a Minimun Radius field controls the size of the arc in corners after a tool radius offset. Most machine tools will then be able to accurately represent the contour in concave corners. This allows PowerMILL to use the nominal tool size to check for collisions, but last-minute corrections for the physical tool size can be applied on the machine.

Protected Toolpath Radius

Profile Radius

PM 14 2D Feature Sets

Documents

Transcript of PM 14 2D Feature Sets