CADD centre training services mold design using (BookZZ org) kho tài liệu bách khoa

I ft � Fig 1.17: Transfer Mold Rotational molding Rotational mol ding is a versatil e p roce ss for creating many kinds of mostly hollow pl astic p arts.. Fig 1.29: Single Cavity mold

Look for the Authentic

CADD Centre Hologram!

Pro/ENGINEER

Reference Guide

Pro IE NG I N E E R '

W I L D F I R E

CONTENTS

1 Introduction to Basic Mold .. . .. . 3

Basic about Mold 3

Applications 4

Mold manufacturing processes - - 4

Machining 4

Plastic materials 5

Molding Machine 7

Molding Process 9

Mold t'f?tC: 1()

Parts of mold 1 6 Single Cavity mold 21

Multy cavity mold .:::··· 21

Family Mold 22

Side Core Et Side Cavity 22

Methods of actuation . . . . . . 22

Feed system 23

Shrinkage 27

Ejection . . . . . 27

Draft 29

Parting surface 30

2 Reference Model creation . . ... .. ... 35

Creating Rib Features . 35

Creating Draft Features . . 37

Analyzing Draft Hinges and Pull Direction . 41

Design Model Analysis . 48

Mold Model . . .. . 54

Modifying the Default Pull Direction . . 56

Analyzing Model Accuracy 59

Creating the Reference Model 62

Redefining the Reference Model 67

Analyzing Mold Cavity Layout . 72

-Pro IE NG I N E E R' t I L D F I R E 3 Preparing Mold M odels ··· ··· -··· 91

S hrinkage . -··· 91

Workp iece 102

Recl assify ing Mol d Model C omp onents . _ . 110

Mol d Vol ume C re ation 113

C reating S liders 117

Re fe re nce Part: C utout : 129

Lifter Mol d Volumes 132

S ke tching Inse rt Mol d Vol ume s � 142

Parting Line and Parting S urface C reation 148

4 Creating Mold 217

Spl itting the Workp ie ce 218

Spl itting Mold Vol umes 221

Blanking and Unbl anking Mol d Ite ms 231

Analy zing Split Cl assification 236

Mol d C omp one nt Extraction 241

Mold Features C reation 246

Waterl ine C ircuits 246

C re ating Sp rues and Runners 258

Ejector Pin Cl earance Holes 266

Fill ing and Op ening the Mold 279

Op ening the Mol d 281

Draft C hecking a Mold Ope ning S tep 288

Inte rfe re nce C hecking a Mol d Op ening S tep 292

Vie wing Mol d Information 295

5 Project ··· ··· ···-···-··-·-··· ··· ··· · ··· ··· 321

CENTRE

0 Basic about Mold

0 Mold manufacturing processes

0 Single Cavity mold

0 Multi cavity mold

A mold is a holl owe d-out bl oc k that is fille d with a l iquid l ike pl astic , glass, metal, or c eramic raw material s The liquid harde ns or sets inside the mol d, adop ting its shap e A mol d is the opp osite of a c ast The manufac ture r who makes the molds is c all ed the mol dmake r A rel ease age nt is typ ic ally use d to make removal of the hardened/set substanc e from the mol d easier

Fig 1.1 : Mold Component

History

1851 by Ale xande r Parks Hy att imp roved it so that it c oul d be p roc essed into finished form In 1872 John, with his brother Isaiah, p atented the first injec tion mol ding mac hine This mac hine was relatively simp le

c omp ared to the mac hine s we use today It basic ally worke d l ike a l arge hyp odermic needle injec ting

pl astic through a heated cyl inde r into a mold The industry p rogre ssed sl owly over the y ears p roduc ing

c reated a huge de mand for inexp ensive, mass-p roduc ed p roduc ts The industry has evol ved ove r the years from p roduc ing c ombs and buttons to p roduc ing a vast array of p roduc ts for many industries incl uding automotive , medic al , aerosp ac e, c onsume r, toy s, p lumbing, p ac kaging, and c onstruc tion

CADD CENTRE

4 Pro IE NGIN EER

Applications

Injection molding is used to create many things such as mil k cartons, containers, bottl e cap s, automotive dashboards, p ocket combs, and most other pl astic p roducts avail abl e today Injection mol ding is the most common method of p art manufacturing It is ideal for p roducing high volumes of the same object S ome advantages of injection mol ding are high p roduction rates, high tol erances are rep eatable, wide range of material s can be used, l ow labour cost, minimal scrap l osses, and l ittl e need to finish p arts after mol ding

S ome disadvantages of this p rocess are exp ensive equip ment investment, running costs may be high, and

p arts must be designed with mol ding consideration

Fig 1.2: Application

Mold manufacturing processes

Mold is the common terms used to describe the tool ing used to p roduce pl astic p arts in mol ding Traditionally, mol ds have been exp ensive to manufacture They were usually only used in mass p roduction where thousands of p arts were being p roduced Molds are typ ically constructed from hardened steel , p re­hardened steel , al uminium, and/or beryl lium-copper all oy The choice of material to build a mol d from is,

p rimarily one of economics, steel mol ds generally cost more to construct, but their longer l ifesp an will offset the higher initial cost over a higher number of p arts made before wearing out Pre-hardened steel mol ds are l ess wear resistant and are used for lower vol ume requirements or l arger comp onents The mol ds can be manufactured by either CNC machining or by using El ectrical Discharge Machining p rocesses ·

Machining

Mol ds are built through two main methods: Standard machining and EDM S tandard Machining, in its conventional form, has historically been the method of buil ding injection molds With technol ogical devel op ment, CNC machining became the p redominant means of making more compl ex mol ds with more accurate mol d details in l ess time than traditional methods

CADD

CENTRE

ProlEN G I NEER

The elect rical discharge machining (EDM) or sp ark erosion p roc ess has bec ome widety used ·n fT'Ol1J croking

As well as all owing t he format ion of shap es which are diffic ult t o mac hine, the p rocess alto 'IS pre-r.aroe_reo

mol ds to be shap ed so t hat no heat t reat ment is required C hanges t o a hardened mol d by convo n!iona

drill ing and mill ing normally require anneal ing t o soft en t he st eel , foll owed by heat t reatment to haroen

it again EDM is a simpl e p rocess in whic h a shap ed el ect rode, usually made of copper or grap hit e, is very slowly lowered ont o t he mol d surface (over a p eriod of many hours), whic h is immersed in p araffin oil A

volt age appl ied bet ween t ool and mol d causes sp ark erosion of t he mol d surface in t he inverse shap e of

t he el ec trode

Fig 1.3: Machining processes Plastic materials

Pl ast ic is sy nt het ic p oly mer of high mol ecul ar weight It is comp osed of organic chemical unit s Poly mer

is a single l arge mol ecul e It is formed as a result of t he union of t wo or more mol ec ules of simpl er substance

Plast ic are normal ly cl assified int o 2 c at egories:

Plastics

Fig 1.4: Type of Plastics

CADD CENTRE

-Thermoplastic

Pro I E NG I N EE R'" L D F I R E

A thermoplastic is a polymer that turns to a liquid when heated and freezes to a very glassy state when, cooled sufficiently Thermoplastics are elastic and flexible "thermoplastic materials can be remelted without undergoing any appreciable chemical change and you reuse" '

Thermoplastics materials are as follow:

• Polypropylene (PP), Ex: Automobile components etc

• Polystyrene (PS), Ex: Toys, Paper weight etc

• Polycarbonate (PC), Ex: Helmets etc

• Polyamide (PA) Ex: Ropes, gears etc

0 Properties

The following are the properties of thermoplastic :

• Possesses high glass sparkle

• Transparence

• High mechanical crack resistance

• Soft and flexible

Thermosetting

Relating to a compound that's softens when initially heated, but hardens permanently once it has cooled Thermosetting materials are made of long-chain polymers that cross-link with each other after they have been heated, rendering the substance permanently hard Thermosetting materials can not be remelted and you can not reuse

Thermosetting materials are as follow:

• Polyurethane

• Alkyds, Ex: Pressure vessels, jigs & fixtures etc

• Polyesters, Ex: Automobile parts etc

• Epoxies, Ex: Switches, Connectors etc

0 Properties

The following are the properties of thermosetting plastic:

• High Thermal stability

• High dimensional stability

• High rigidity and hard ness

CENTRE

A feed hopper is for hol ding and feeding the pl astic material in to barrel

Pro I E NG I N E E R'

L D F I R E

Extrude screw

The screw of an injection molding machine is d ivided into th ree sections or zones

• The feed section

• The com pression section

• The meteri ng section

The feed section transports the p lastic material from the hopper to heated portion of the barrel The plastic

g ra n u le is compressed to a homogeneous melt in the com p ression section:"

The fi nal mixin g and heating of the material into a homogeneous melt is ca rried out in the meteri ng zone The d rive for the rotation of screw during feed cycle is obta i ned from a hyd ra u l ic motor or a va riable speed electric motor

Fig 1 7: Extrude Screw

Pr o l E N G I N E E R

\'/ L D F I R E

Molding Process

The chart below explains the Molding process

Assigning • mold number

L Mo'd desig!l review Mold making

- 1.Mold·base molding

Tt review seminar

�- J,: : - � The d"imensiOn of finished

._� � rod - ucts '- tnspectio �-'"- n _ ,

Blow molding is intended for use in manufacturing hollow plastic products It is a process used to produce

hollow objects from thermoplastic In general, there are three main types of blow molding: Extrusion blow

molding, injection blow molding, and stretch blow molding

The blows molding process begins with melting down the plastic and forming it into a parison or perform

The parison is a tube-like piece of plastic with a hole in one end in which compressed air can pass

through

The basic process has two fundamental phases First, a perform (or parison) of hot plastic resin in a

somewhat tubular shape is created Second, a pressurized gas, usually air, is used to expand the hot

preform and press it against a female mold cavity The pressure is held until the plastic cools This action

identifies another common feature of blow molded articles Part dimensional detail is better controlled on

the outside than on the inside, where material wall thickness can alter the internal shape Once the plastic

has cooled and hardened the mold opens up and the part is ejected

Fig 1.10: Blow Mold

-CADD·

CENTRE

a (j

t

The mac hine use d to e xtrude mate rial s is ve ry simil ar to an injec tion moul ding mac hine A motor turns

a sc re w whic h fee ds granule s of pl astic through a he ate r The granule s mel t into a l iquid whic h is force d through a die , forming a l ong 'tube l ike ' shape T he shape of the die de te rmine s the shape of the tube T he

e xtrusion is the n c oole d and forms a sol id shape The tube may be printe d upon, and c ut at e qual inte rvals The piece s may be rolle d for storage or pac ke d toge the r S hape s that c an re sult from e xtrusion incl ude T-sec tions, U-sec tions, square sec tions, I-sec tions, L-sec tions and c irc ul ar sec tions

Fig 1.11 : Extrusion mold

Injection mo l ding

Injection mol ding is a manufac turing proce ss for produc ing parts from both thermoplastic and thermosetting

pl astic mate rial s Mate rial is fe d into a he ate d barre l, mixe d, and force d into a mol d c avity whe re it c ool s and harde ns to the c onfiguration of the mold c avity Afte r a produc t is de signe d, usually by an industrial

de signe r or an e nginee r, mol ds are made by a mol dmake r (or tool make r) from me tal , usually e ithe r steel or aluminium, and prec ision-mac hine d to form the fe ature s of the de sire d part Injec tion mol ding is widely use d for manufac turing a varie ty of parts, from the smallest c ompone nt to e ntire body panel s of c ars

Injection Mold ( VERTICA L TYPE )

Bar S l o Dowel Pin

& Bush111g

T m G ate

CENTRE

Fig 1.13: Calendaring Thermoforming

The thermoforming process consists of heating thermoplastic sheet to its softening temperature and forcing the hot and flexible material against the contour of the mold by mechanical (Ex: Tools, plugs, Solid molds.)

or by Pneumatic means air pressure created by pulling a vacuum or using the pressure of compressed air When the mold is cooled the plastic retains the shape and details of the mold

CENTRE

@ Colored Sheet@ Pressure and

is Pre Heated Vacuum are

to Soften for Applied to Process Form Part

@ Part is Removed Trimmed and Machined to Complete Fig 1.14: Thermoforming

Pro I E N G I N E E R '

W l l D f l R E

Reaction injection molding

Reaction injection molding (RIM molding) is similar to injection molding except that a reaction occurs within the mold The process uses thermoset polymers (commonly polyurethane) instead of thermoplastic polymers used in standard injection molding Before injection of the polymer two components are mixed which react in the mold to form a solid thermoset polymer The bi-component fluid is of much lower viscosity than molten thermoplastic polymer which enables the economical production of large parts with complex geometry

CADD

CEN'TRE

·

-Gravity

(1)

Transfer molding

Upper mold half

Lower mold half

Transfer molding, like compression molding, is a process where the amount of molding material (usually

a thermoset plastic) is measured and inserted before the molding takes place The molding material is preheated and loaded into a chamber known as the pot A plunger is then used to force the material from the pot through channels known as a sprue and runner system into the mold cavities The mold remains closed as the material is inserted and is opened to release the part from the sprue and runner The mold walls are heated to a temperature above the melting point of the mold material; this allows a faster flow

of material through the cavities

Transfer Molding is an automated operation that combines compression-, molding, and transfer-molding processes This combination has the good surface finish, dimensional stability, and mechanical properties obtained in compression molding and the high-automation capability and low cost of injection molding

and transfer molding Transfer Molding is having a "piston and cylinder"-like device built into the mold so

that the rubber is squirted into the cavity through small holes A piece of uncured rubber is placed into a portion of the transfer mold called the "pot." The mold is closed and under hydraulic pressure the rubber or plastic is forced through a small hole (the "gate") into the cavity The mold is held closed while the pla�tic

or rubber cures The plunger is raised up and the "transfer pad" material may be removed and thrown away The transfer mold is opened and the part can be removed The flash and the gate may need to be trimmed

Another key point is that a premeasured amount of thermosetting plastic in powder, preform, and even granular form can be placed into the heating chamber

CADD

CENTRE

Pro I E N G I N E E R

W ) I ft �

Fig 1.17: Transfer Mold Rotational molding

Rotational mol ding is a versatil e p roce ss for creating many kinds of mostly hollow pl astic p arts The

p hrase is often shortened to rotomolding

A heated mol d causes the pl astic resin within to melt and form a p uddl e at the bottom of the mold cavity The mold is then sl owly rotated (usually around two p erp endicular axes) causing the mel ted p lastic to fl ow into to the mold and stick to its wal l s In order to maintain even thickness throughout the p art, the mol d continues to rotate during the cool ing p hase

Rotational molding

Powder Mold

char9in9

0 Fig 1.18: Rotational Mold

CADD CENTRE

• Core retainer or core plate

• Cavity retainer or cavity plate

Fig 1.20: Cavity Insert

Fig 1.21: Core a Cavity insert Assembly

Core retainer or core plate

It retain core insert The section that is engaged in opening I closing movement is called a core plate The core plate leaves a trace on a part, because it has an ejector pin to push the part

Fig 1.22: Core plate

CADD' CENTRE

It retains Cavity insert The cavity plate has a sprue bush, which is the entrance for molten plastic

Fig 1.23: Cavity plate

Back plate These plates are placed bottom of the core plate and over the cavity plate These plates do not allow the core and cavity insert to come out of the core and cavity plates

Ejector plate This is placed to bottom of ejector retainer and clamped together this does not allow the ejector pins and return pins to come out from ejector retainer This has provision to hold the ejector rod This plate transmits the force from the actuating system of the injection machine to the molding via an ejector rod

Ejector retainer

This Retains the ejector pins and return pins

Fig 1.24: Ejector Plate and Ejector retainer

Paral lel block These plates provide enough space to operate the ejection system

Height of the parallel block =Thickness of the ejector assembly + Thickness of the rest buttons head +

required movement

CENTRE

These are fixed to bottom plate or bottom of ejector plate Rest buttons reduces the effective seating area

· Sprue bush

-Pro E N G I N E E R , _ D F I R E

This is a tapered hole this works as passage between nozzle of the macnfoe a:-o t".J"'ner of the mould It is fixed in top plate of the mold

Fig 1.27: Sprue bush

Sprue pul ler

When the mold opens it is essential that the sprue is pulled positively from the sprue bush Sprue puller is provided to pull the sprue in case of multy cavity mold

Register ring The material is to pass without hindrance into the mold The nozzle and the sprue must be correctly aligned Register ring aligns the mold to center of machine

Pro l E N G I N E E R

W l 0 F R E

Mold assembly

The following picture shows simpile mold assembly

Fig 1.28: Mold Assembly

Single Cavity mold

In this we will have only single core and cavity You produce only one component at a time

Fig 1.29: Single Cavity mold Multy cavity mold

If you create more than two or more cavity is called multy cavity mold

Number of cavities: Ones the order is finalized and the design is going to start, the discussion should be weather Single cavity or multy cavity mold should be used Points to be taken into consideration:

• Number of components to produce and period of delivery

• Injection molding machine and machine capacity (Tonnage)

• Cost of molding

CADD

CE IT.RE

-Pro l E N G I N E E R"

Family Mold

In one mold create two or more different components

Fig 1 30: Family mold

Side cores are used for forming a hole or recess in the side face of a component It is normally mounted

on at right angle to the mold axis

Side cavity is used for the formation of projections in the side face of molding

The side cavity must be with drawn prior to ejection

Advantages:

• The mold is simple and there fore less expensive

• Ease of operation and less production difficulties

• No flow line will develop

Methods of actuation

Fig 1 31 : Side core

The side core or side cavity assembly is actuated by three methods:

Pro l E NG I N E E R

Finger cam method of when a short delay period is required The amount of clearance between cam and cam hole determines the delay time The finger cam should be sufficient length to withdraw the side core completely from the molding

The dog leg cam method is used when a longer delay period is required It is desirable to withdraw the molding completely from the fixed half before retracting the side core This ensures that the molding remains in the moving half in readiness for ejection

The spring loaded system is used for molding with shallow undercuts or projections

Fig 1.32: Cam Actuation

Feed system

It is necessary to provide a flow way in the injection mold to connect the nozzle of the injection machine

to the impression The floe way is termed as feed system Normally a feed system consists of a sprue, runner and gate

It is seen that the material passes through the sprue, main runner, branch runner and gate before entering the impression

CADD CENTRE

Runners should polish (glass finish)

While designing runner the following points to be considered:

• It should be small as possible

• It should be equal in length to all cavities

• It should ensure simultaneous filling of all cavities

Fig 1.34: Runner

CADD

CENTRE

Conventional Improved Balanced "H" Circular

Fig 1.35: Runner layout

Machining and ejection of square and round are difficult To overcome the problems trapezoidal runners

are mostly designed

-Pro I E NG I N E E R'

- D F I R E

A gate should be designed such that:

• Freeze soon to avoid suck back: When the nozzle is taken back after injection, the material from

cavity should not tend to go back to the runner

• Easy degating: Breaking the component from runner should be easy

• Small witness mark: The gate should not leave a witness mark on the component

• Better control over flow rate: Gate dimension can be adjusted to achieve better flow and filling rate

• Over lapping gate

• Self cutting gate

Fig 1.37: Gate

Cooling

molding runner

branch runner Fig 1.38: Feeding system

I

Hot material is injected into the mold It cools rapidly to a temperature at which it solidifies to retain the shape of the impression after ejection The temperature mold has a major influence on the mold cycle time Melt flows freely in a hot mold But grater cooling period is required If the mold cools quickly the melt will not reach the extremities of the impression

To maintain the required temperature water is circulated through holes or channels within the mold These holes or channel are termed water ways The complete system of water ways is termed as circuit

It has both inlet and outlet

CENTRE

Shrinkage increases with:

• Increase of material temperature

• Increase in section thickness

Shrinkage decreases with:

• Higher cavity presser

• Longer injection time

Several ejector systems can be used:

• Ejector pin or sleeve

"Pro\ENG\NEER'

W I L D F I R E

Stripper p l ate

A stripper plate or ring is used when ejector pins or valves would not operate effectively The stripper plate

is often operated by means of a draw bar or chain

Thread ejection

When the threaded component is to eject it makes core to rotate This is done by connecting gear from

rotating member to the ejector pins, rack and pinion etc

Draft

A draft angle describes the amount of taper for molded parts perpendicular to the parting line

Consider the fabrication of a hollow plastic box, without lid Once the plastic has hardened around the

mold, the mold must be removed As the plastic hardens, it may contract slightly By tapering the sides of the mold by an appropriate "draft angle", the mold will be easier to remove

If the mold is to be removed from the top, the box should taper in towards the bottom, such that measuring the bottom internal dimension will yield a smaller length and width than measuring the top from which the mold is extracted

By specifying the opening length and width, a draft angle, and a depth, it is not necessary to specify the dimensions for the internal surface, as these may be calculated from the above

The manufacture of a part that incorporates zero or negative angles may require a mold that can be separated into two or more parts, in order to release the molding

·

-Pro I E NG I N E E R

:> F I R E

Parting surface

The portions of both the mold plate which butt together is the parting surface, the parting surface forms

a seal and prevents the loss of plastic material from the impression

Parting surface are classified as flat and non flat The non flat parting surface includes stepped, profiled and angled surfaces

The nature of parting surface depends on the shape of the component A parting surface must be so chosen that the molding can be ejected easily from the mold

It the parting surface are not properly matched the material from the impression will escape through the gap This material is called Flash

CENTRE

0 Creating Rib Features

0 Creating Draft Features

0 Design Model Analysis

0 Mold Model

0 Modifying the Default Pull Direction

0 Analyzing Model Accuracy

0 Creating the Reference Model

0 Redefining the Reference Model

0 Analyzing Mold Cavity Layout

Pro IE NG I N E E R

N L D F I R E - 11

2 Design Model Creation

In this chapter, you will learn about the basic mold process in Pro/ENGINEER that is typically used to take

a part from its design stage to the creation of its mold

P reparing and Analyzing Design Models

When you create a mold for a design model, you should first inspect the model and analyze it to verify that

it is indeed ready to be molded Typically, the reference model geometry that you use for a mold model is derived from the design model You can analyze the design model and reference model for adequate draft features and consistent thickness, adding draft features if necessary It is critical that the final reference model should have sufficient draft, so that it can be cleanly ejected from the mold

Even though the design model you receive may be a valid design model, you may not be able to use the model to create a robust mold The following items are typically required for the design model to create a robust mold and part:

• Draft - Facilitates the removal of the part from the mold

• Uniform thickness - Areas of a part that are thicker than others, which can result in sink zones or warping when cooling occurs

• Ribs - Adds strength and rigidity to the molded part

Guidelines for Proper Design Model Preparation

The following are some guidelines for proper preparation of a design model for molding

• Try to create models that are of uniform thickness, to prevent sink zones or warping in the resulting molded part

• Create ribs that are approximately half the model's wall thickness to prevent sink Apply draft to the rib walls if they are "vertical" faces Vertical faces are those that are vertical with respect to how the mold opens

• Apply draft in the proper direction at least 0.5 degrees on all "vertical" faces Draft has been applied

to all faces that are vertical with respect to how the mold opens

• When creating Draft features in Pro/ENGINEER, either reorder them to be created before any related rounds or insert them before the rounds This practice results in a more robust Pro/ENGINEER model

Creating Rib Features

Ribs are typically used to strengthen parts A rib feature is similar to an extruded protrusion, except that t requires an open section sketch The rib also conforms of existing planar or cylindrical geometry when · i :S extruded After you select an open section sketch and set a thickness, Pro/ENGINEER automatically crea� the rib feature by merging it with your model The system can add material above or below the ske:cr c: c the thickness can be applied on either side or be symmetric about the sketch The Rib tool enao 5 = create rib features faster than it would be for you to create and sketch a protrusion

CADD C� -r:RE

The following task explains how to create rib:

Pro I E NGIN E E R'

1 Open Rib_Feature.prt

�

2 Start the Rib Tool i � / from the Feature tool bar Select RIB_SKETCH-1 Specify the width as 7 5

Fig 2.1: Rib Feature with neutral option

3 Click Complete Feature _.,

4 Start the Rib Tool rb/ Select RIB_SKETCH-2 Specify the width as 25 The rib is centered about the

sketch

Fig 2.2: Rib Feature with Neutral

5 Click Change Thickness Option X The rib moves to the left of the sketch as shown below

Fig 2.3: Rib Feature Created left of sketch

CADD

CENTRE

7 Start the Rib Tool � Select RIB_SKETCH-3 Specify the width as 10mm

Fig 2.4: Rib Feature above from sketch

8 Click the yellow arrow in the graphics window The rib is now below the sketch as shown

9 Click Complete Feature

This completes the task

Creating Draft Features

Fig 2.5: Rib Feature Flipped to below sketch

You can use draft features as finishing features in molded and cast parts or anywhere sloped or angled surfaces needed to be created You can define several types of draft features by selecting different combinations of curves, edges, surfaces and planes for the draft surfaces, draft hinges, pull direction and split plane (optional) Drafts can add or remove material from a model

A basic draft feature consists of the following four items:

Draft surfaces - These are the surfaces that are to be drafted You can select a single surface, multiple individual surfaces or loop surfaces as the draft surfaces

Draft hinge - Determines the location on the model that remains the same size after the draft is created

CADD

CENTRE

-Pro I E N G I N E E R" .� l 0 F l R E

The draft surfaces pivot about their intersection with this plane The� nttd not have to be a physical intersection Rather, the intersection can be extrapolated You can select a datum plane, solid model surface, curve chain or surface quilt as the draft hinge

Pull direction - Direction that is used to measure the draft angle The pull direction is also called the reference plane By default, the pull direction is the same as the draft hinge The direction reference is used to define the draft angle direction and the draft angle is measured normal to this reference You can select a datum plane, planar model surface, linear reference such as an edge or two points, or a coordinate system axis The mold opening or pull direction is usually normal to this plane

Draft angle - Values range from -30 degrees to +30 degrees When you specify the draft angle, you can

reverse the direction by which the material is added or removed by entering a negative value or by clicking the Reverse Angle icon X in the dashboard or by right-clicking on the angle drag handle and selecting Flip Angle

The following task explains how to create a Draft:

Draft Cylinder surface

Fig 2.6: Draft Cylindrical surface

3 Click Complete Feature ,,

Draft surfaces

4

5

Open Draft.prt

Start the Draft Tool 1I> Select the References tab In Draft surface Press CTRL and select the four

vertical surfaces, to draft them Select the top surface of the main protrusion for draft hinge Edit the

draft angle to -1 o

CENTRE

Pro l E N G I N E E R

6 Click Complete Feature 1 -itl'

This completes the task

Creating Basic Split Drafts

Fig 2.7: Draft Surfaces

Split draft enables you to apply different draft angles to different portions of a surface

Split options include:

• No split

• Split by split object

Select a plane:

• Split by Split Object - Splits the draft using a specified datum plane or surface

• Split by Draft Hinge - Splits the draft using the specified draft hinge

Side options:

• Independently

• Dependently

• First/Second side only

Fig 2.8: Drafting First Side Only

Pro E N G I N E E R

L i) F R E

Fig 2.9: Drafting Sides Dependently Fig 2.10: Drafting Sides Independently

The following task explains how to create a split draft:

1 Open Draft_Split.prt

2 Right -click and click Edit the definition on Draft 1 in the Model Tree

3 In the dashboard, select the Split tab Select the Split option to Split by draft hinge Select Split Side

option Draft first side only

4 Click Complete Feature � _

Fig 2 l l : Drafting First Side

5 Right -click and click Edit the definition on Draft 2 in the Model Tree Select the Split option to Split

by draft hinge Select Split Side option as Draft sides independently

-cENTRE

Pro i E N G I N E E R

W I L D F I R E

Fig 2.12: Drafting Sides Independently

6 Right -click and click Edit the definition on Draft 3 in the Model Tree Select the Split option to Split

by draft hinge Select Split Side option as Draft sides dependently

7 Click Complete Feature �

This completes the task

Fig 2.13: Drafting Sides dependently

Analyzing Draft Hinges and Pull Direction

By default, the pull direction is the same as the draft hinge However, yoCJ can select different references for the draft hinge and pull direction

CENTRE