Mold Design

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Pro/MoldDesign

http://ww w.me.umn.edu/courses/old_me_course_pages/me5221/Tutoria...

ME 5221 Computer-A Computer-Ass ssisted isted Product Prod uct Realization: Realizatio n: Lab ME5221 Tutorial: Tutorial: Introduction to Pro/M Pro/MOLDESIGN OLDESIGN Pro/E Wildfire 2.0 Intent The goal here is to introduce the injection molding molding mold mold design design process by providing providing a mold design exercise and a set of step-by-step instructions to carry out the exercise. The task is to create cre ate two mold plates plates for f or the molding of a part pa rt (solid model) model) that is provided. The mold plates are the parts that then can be used in the generation of machning programs for producing the mold. This tutorial is viewed as a starting point that interested This intere sted indivi individuals duals can use to investigate all facilities. Only some important mold characteristics and procedures are described here.

Overview The general general mold design design procedure is - starting start ing with a part model, a workpiece model and an empty mold creation creat ion space provided by the proMOLDESIGN proMOLDESIGN program program create an assembling of the reference/part model(s) and the workpiece model(s) include and check draft account for shrinkage, either by individual dimensions or isotropic shrinkage define parting surfaces(s) and volumes extractt the mold extrac mold volumes from the model that can ca n be used in mold production/machining production/machining these are the mold plates extracted from the overall mold model add gates, runners, cooling lines lines assemble mold mold and mold base, etc. etc . check for f or mold opening opening interfer interference ence add ejector system And, with the mold plate model modelss the machining machining programs programs can be developed. deve loped. This exercise This e xercise involves - assembling a design part and workpiece into a mold assembly, - shrinking the part pa rt model, - defining parting surfaces to use in splitting the mold, - extracting extra cting mold mold components to obtain a part model and mold plate models.

Manufacturing Models The Part or Design Model is the model based on intended function of the product. The Reference Model  includes manufacturing process specific characteristics and features needed for the  part production process, e.g., draft, shrinkage shrinkage consideration, etc. In a rough sense it's a model model of the mold cavity. The reference referenc e model is assembled assembled with the Workpiece Model to form the Mold Assembly. This occurs in an initially empty space provided by the program when the manufacturing part of the software is started.

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The reference model model can be a separ separate ate m model odel or the the desi design gn m model odel can be designated designated to be the reference model. model. During design - changing the Reference model/part does not change the Design part, - changing the Design model changes the Reference part. Components and features can be extracted from the mold model and used, e.g., a mold plate model can be used in Pro/NC to create toolpaths and generate code to machine the component.

The two models to be used are the design model  model shelf2004.prt  shelf2004.prt  and  and the workpiece model workpiece_mold.prt  which  which are Pro/Engineer models and available under Part Files on the course web site. These parts are a re dimensioned in mm. mm. The part and workpiece have to be assembl a ssembled ed to form f orm a mold which which will "work" "work" - that t hat is, open ope n and allow  part ejection. eject ion. So So it is important important to understand the molding process and the te termin rminology ology used, and to have a  plan about how the part and workpiece model will will be assembled (part model location location in the workpiece which will will then be split along a parting plane to produce tthe he two mold plates). For example, if the intent is to place the reference part model in the workpiece by aligning coordinate systems, it is logical logical when creating crea ting the workpiece model to include a coordinates system at the location locat ion of  the parting pa rting line, line, either by explicitly specifying specifying a coordinate system or extruding extr uding in both directions direct ions when using the extrude capability to create the workpiece model.

Start Pro/Engineer  Mold Assembly The mold creation process starts with the empty Assembly model provided and the reference and workpiece are assembled to it. File -> New... New... Manufacturing -> Mold Cavity name the moldfile the  moldfile and  and OK in New dialog box MOLD menu and Mold Cavity toolbar become available A coordinate system with feature/operation planes is supplied

This is a starting feature system into which the reference part and the workpiece will be assembled and then split to create the mold model. Especially note the coordinate system and orig or igin in location as these will will be used in placing the mold mol d components (reference (refere nce model and workpiece model) to form the mold. mold. Main_Parting_Pln Pull_Direction Pull_Di rection is the t he direction in which the t he mold opens, it's probably the positive positive z-direction z-direct ion Mold_Front Mold_Right

Edit Units->  inSetup ASSEM SETUP menu choose system of units to work in Set OK to warning

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Close Units manager  Done in ASSEM SETUP Mold Model in MOLD Assemble in MOLD MODEL Ref Model in MOLD MDL TYP

in the Open dialog box, select the file for the part model and Open especially note the part model coordinate system syste m as it will be used for alig aligning ning part and workpiece models and assembly space starting the assembly process with the part model in the Component Placement Place ment dialog box box choose the type of placement - and to use coordinate systems  pull down the Constraint Type Type list and choose Coord Sy Syss with (preselected) (preselecte d) Select in GET COORD S  pick/click on the reference part coordinate system and then the mold coordinate system OK in Component Component Placement P lacement dialog box if Placement Place ment Status is Fully Fully Constrained To copy design part to reference part  and OK in Create Reference dialog box Merge by Ref  and OK  in  in the Create Reference Model dialog box

continuing by assembling the workpiece model Mold Model in MOLD Assemble in MOLD MODEL Workpiece in MOLD MDL TYP in the Open dialog box, select workpiece file and Open in the Component Placement Place ment dialog box box choose type of placement, and to use coordinate systems  pull down the Constraint Type Type list and choose Coord Sy Syss click on the workpiece coordinate system and then the mold coordinate system (this may be listed as a PRT_CSYS_DEF) OK in Component Placement dialog box if Fully Constrained Assess alignments, alignments, pull direction, parting plane, etc. e tc. Evaluate coordinate systems, MAIN_PAR MAIN_PARTING TING_PLN, _PLN, etc., e tc., to assure a ssure process/mold opening will will work. Done/Return in MOLD MODEL

Shrinkage

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The part produced will be smaller than the mold cavity since plastics shrink on cooling and solidification. Accounting for  shrinkage can be included in the reference model in several ways. In the shrinkage facilities a shrinkage feature is created and applied to the reference model. The shrinkag shr inkagee factor, S, is used to specify shrinkag shrinkagee - positive value to generate generate a larg larger er reference model, and hence larger  mold cavity. Shrinkage can be based on the original geometry using the formula (1 + S), or based on resulting geometry using the formula (1 / ( 1 + S )) SHRINKAGE by Dimensions - applies to the design model, - can specify different shrinkage in individual, different dimensions, - individual shrinkage shrinkage values override overall model shr shrinkag inkagee value. SHRINKAGE by Scale when done in MOLD mode the shrinkage feature is in the reference model, not in the design model, when done in PART mode the shrinkage feature is created in the design model.

For Shrinkage by Dimensions Shrinkage in MOLD By Dimension in SHRINKAGE  preselected  preselecte d 1 + S for Formula Formula in Shrinkag Shrinkagee by Dimensions Dimensions dialog dialog box box note that formula is 1 + S, so shrinkage ratio may be negative

All Dimensions enter ratio to specify shrinkage  Note that that individual dimension dimensionss can be m manipu anipulated lated in By Dim - display dimensions, set shrinkage by pick/click on dimension and supply shrinkage ratio S - for  each dimension

green checkmark to accept mold is displayed with shrunk/expanded reference part - Set/Reset in SHRK BY DIM can be used to change shrinkage

- shrink information is available Shrink Info Info in SHRINKAGE Done/Return in SHRK BY DIM Done/Return in SHRINKAGE

To Apply Shrinkage by Scaling Sca ling MOLD -> Shrinkage Shrinkage By Scaling in SHRINKAGE  preselected  preselecte d 1 + S for Formula Formula in Shrinkag Shrinkagee by Scaling Scaling dialog box Isotropic enter Shrink Ratio PRT_CS PRT _CSYS YS_DEF: _DEF:F1 F1 to specify use of part coordinate system  pick/click on model model coordinate system green checkmark 

- shrink information is available Shrink Info in SHRINKAGE

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Done/Return in SHRK BY Scaling Done/Return in SHRINKAGE

Creating Parting Surface(s) Create a parting surface parallel to mold face. This plane will be used to define (separate) the workpiece into two mold plates. Parting surfaces are useful -- can define parting surfacesurfaces and usetoit split in splitting workpiece along it also use parting a volume --- e.g., split the workpiece into one or more volumes instead of creating the volumes Parting surfaces must be created before they are used. Regarding parting surfaces; - finished parting surface must completely intersect workpiece or volume to be split - parting surface cannot intersect itself  Of the methods for creating parting planes perhaps the most useful are Copy - is handy since this uses an existing plane, Extrude - can be used to create a complex parting surface, e.g., extrude a line Offset - create a plane offset from an existing plane.

Example use of extrude MOLD -> Parting Surf -> Create

enter name for the parting surface and OK in Parting Pa rting Surface Surface Name dialog box box Add in SURF DEFINE (preselected) Extrude  in SURF OPTS Done in SURF OPTS Done in Attributes, since defaults can be used

createe a plane larger than the mold plate creat plate by creating cre ating a line line and extruding it across the mold/workpiece mold/workpiece define a sketching plane on a mold face, (preselected) Setup in SETUP SK PLN, Plane  in SETUP PLANE, Pick  in  in GET SELECT  pick a workpiece surface to to sketch sketch tthe he line on that that will be extruded across th thee work surface to form form  parting plane and either use the direction shown OK  or   or Flip (preselected) Top in SKETVIEW, Plane  in SETUP PLANE, Pick  in  in GET SELECT the prompt is to pick reference planes Close the Reference information box when Fully Placed draw a line across th thee mold face, Sketch -> Line draw a line completely across and extending past the ends of the workpiece Done  in Sketch

extrude the line across the mold to create the parting plane, (preselected) Blind in SPEC TO Done  in SPEC TO specify extrusion length - larger than workpiece size OK  is  is Surface: Extrude information box

Done/Return in SURF DEFINE Done/Return in PARTING SURF

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Mold Volumes, Mold Components - Splitting the Mold To define mold volumes a parting plane plane is needed and it should be parallel to one of the mold faces. The definitions used in Pro/Mold are that; - mold volumes have no solid solid material, they are surfaces that t hat define a closed volume in space. V Volumes olumes are intermediate steps in the process of moving from workpiece and reference model geometries to solid mold components. - the mold is constructed by building volumes and filling them with material. This is done in the Extract part of the process. - extracted components retain associativity so if a volume volume is modifi modified ed the component is updated on regeneration of the mold model. Splitting does not alter the workpiece - the system copies the workpiece into one or two volumes that can be Splitting used for creating mold components. Spitting reproduces the volume(s). Extract is used to create the mold components after splitting. Splitting can be done using a surface, a parting surface or a volume. In the Split operation the system, - calculates the volume to one side of the parting surface, - converts the split-off volume into a mold volume, - subtracts (trims) the volume of the reference part from the workpiece geometry copied. Since volumes that do not modify existing geometry are created, a one-component split allows for extracting  parts of the workpiece/mol workpiece/mold d witho without ut alteri altering ng the ori origi ginal nal wor workpie kpiece. ce. So, it is possible to create a mold cavity in the workpiece by - split the workpiece to one volume, i.e, copy the workpiece to one volume, - and the system trims the reference part from the geometry copied, - resulting in a solid with the mold cavity in it. Then, split the resulting solid into two volumes at the desired parting plane(s)

To Split to Two Volumes MOLD -> Mold Volume Split in MOLD VOLUME (preselected) Two Volumes and All Wrkpcs in SPLIT VOLUME Done in SPLIT VOLUME

with preselected Pick  in  in GET SELECT, or use of Select by Menu which may be easier  select the parting surface, (it must intersect the entire workpiece and not be blanked) for more complicated molds it may be useful/necessary to create and use more than one parting  plane

Done Sel in GET SELECT OK  in  in Split dialog box

system computes the two volumes, highlights each in turn and prompts for new names

enter volume names for the two volumes sequentially in the Volume names dialog box and OK  Done/Return in MOLD VOLUME

To make the resulting volumes into solid mold components - for both volumes MOLD ->Mold Comp Extract in MOLD COMP select volume desired in Create Cre ate Mold Component Component dialog box and OK 

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same procedure for other volume

Done/Return in MOLD COMP and on Save mold halves are now solid models ( To Split to One Volume

MOLD -> Mold Volume -> Split One Volume and All Wrkpcs in SPLIT VOLUME if mold volumes already exist would have to choose the features of interest from choose All Wrkpcs, Mold Volume or Sel Comp

Done  in SPLIT VOLUME

the Split dialog box opens select an existing parting surface to use to split the workpiece if failure occurs must use Show Errors -> Item Info

select the island to includ i ncludee OK  in  in Split

(moving the cursor over island list highlights islands )

enter name of new volume and OK in Volume Name dialog box Done/Return in MOLD VOLUME

To turn the resulting volumes into solid mold components MOLD ->Mold Comp Extract  in MOLD COMP select volume desired in Create Mold Component dialog box and OK  Done/Return in MOLD COMP

)

Mold Ope Opening ning MOLD -> Mold Opening Define Step in MOLD OPEN Define Move in DEFINE STEP

select the t he part of the mold mold model that moves on mold opening, opening, say by Sel By Menu in GET SELECT, choose the mold component, Select in Selection Tools dialog  box Done Sel in GET SELECT

To select motion direction, say by (preselected) Define Move in DEFINE STEP, Pick  in  in GET SELECT  pick a mold mold edge, or coordinate coordinate system direction, etc. enter a move distance Done in DEFINE STEP Done/Return in MOLD OPEN Mold Opening in MOLD, Done/Return in MOLD OPEN

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Adding Mold Features - Water Line Mold features features are needed to com complete plete the mo mold, ld, e.g., draft, runners, ejector system, etc. As an example, to add a water line - define the water line diameter, - specify the water line by sketching a line between water line end points, --- this requires creating a sketching plane on which to draw the water line path. One way to create a sketching ske tching plane is by offset, and for a water line offseting the sketching pl plane ane from the mold parting pl plane ane is logical. in the Tool Bar  Insert -> Surface -> Offset select the surface to offset from, by, say Sel by Menu in GET SELECT choose the parting surface and Select in Selection Tools dialog box the selected plane that the new plane is to be offset from is highlighted choose direction of offset in SURFACE: Offset dialog box enter offset distance in SURFACE: Offset dialog box and the green checkmark  The offset plane is added and can be used as the sketching plane for the water line.

To create a water line Feature in MOLD Cavity Assem in MOLD MDL TYP Water Line  in MOLD FEAT

enter water line diameter  Sketch a line between the end points of the water line to pick the sketching plane plane (preselected) Setup in SETUP SK PLN, Plane  in SETUP PLANE, Pick  in  in GET SELECT - pick the plane to sketch the line on that will be the water line - and either use the direction shown OK  or   or Flip Top in SKETVIEW, Plane in  i n SETUP PLANE, Pick  in  in GET SELECT the prompt is to pick reference planes Close the Reference information box when Fully Placed

draw a line across the mold face, Sketch -> Line draw a line for the water line completely across the workpiece/mold workpiece/mold plate Done  in Sketch

Auto Add in Intersected Intersecte d Comps dialog dialog box since since default def ault are useable OK in Intersected Intersect ed Comps dialog box box Done/Return in FEAT OPER 

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