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Week 11 - Final project

OBJECTIVE 1. Creation of tooling direction and Perfom draft analysis on the class A surface from the inputs door trim panel, that is Map pocket upper lower, Lower substrate, Door armrest. 2. Creation of Class B and Class C surface and Solide body from the close surface. 3. Ceating attaching feature according to master…

Ankosh Vasave
updated on 29 Mar 2022

OBJECTIVE

1. Creation of tooling direction and Perfom draft analysis on the class A surface from the inputs door trim panel, that is Map pocket upper lower, Lower substrate, Door armrest.

2. Creation of Class B and Class C surface and Solide body from the close surface.

3. Ceating attaching feature according to master section such as flanges heat stakes.

4. Creation of Engineering features heate stakes, ribs, doghouse, 4 way 2 way locatores with thire design guidlines.

5. After all perfom draft analysis on the final part, creation of parting line.

6. Assemble all part togather with the push pines.

INPUT OF DOOR TRIM

Class A surface

The entire visible plastic surfaces you see inside the car Dash board or ip, door panels, etc. are A surfaces. even the visible surface of bumper, fender, mirror housing, etc .Class A surface is a asthetic part of the part which is supposed to be in visual side of a part, which is going visible to the occupant or the viwer. class a side dose not have any engineering features and inpefection.

Class B surface

Class B surface is created according to the class a surface it backside of any part which have all the mounting features or say engineering features like heat stakes, screw bosses , doghouse, and in is not visible to viwer.

Class C surface

Class C surface is the surfcae which connects the class a and class b surface which have some imperfections and flashes this surface is not visible.

PLASTIC DESIGN GUIDE

To ensure a quality part, there are three major areas of focus throughout the design stage:

Proper plastic part design
Proper material selection plastic part design
Processing conditions for plastic injection molding

The designers and engineers at API have over 250 combined years of experience in designing parts for plastic injection molding, selecting materials, and processing resins (specializing in engineering and high performance resins). This guide was designed to demonstrate the basic elements of proper plastic part design.

DESIGNING PARTS FOR UP AND DOWN MOULDING HELPS CONTROL THE COST

Designing a part that can be molded with a "straight pull" or "up & down" motion is a great way to keep the cost of the mold down. A straight pull mold is designed so that when the two halves (A side and B side) of the mold separate from each other, there is no plastic blocking the path of the metal in the direction of the pull. Undercuts on the part cause this blockage of path and require an action in the mold (cams, core pulls, etc.). Action in the mold can have a major impact on the cost (and overall size) of a mold.

UNIFORM WALL THICKNESS HELPS TP PREVENT DFECTS

Proper wall thickness is one of the most fundamental requirements in designing a part for plastic injection molding. Plastic shrinks as it cools which can lead to defects such as sink marks, voids, stresses, and warping. Plastic resin solidifies in the mold nearer to the outside of the part (closest to the mold surface). Thick sections of a part tend to pull inward, creating stresses, sink marks, or voids. Since thinner sections cool quicker, stress can build in the part between thinner and thicker sections, resulting in part warpage.

DRAFT ALLOWS FOR PARTS TO RELEASE FROM THE MOLD

Draft is required on all parts in the direction of mold movement in order to allow parts to release or eject from the mold properly. Draft is the angle in which the part is tapered to allow it to release. As the part cools, it tends to want to shrink to the core side of the mold. Adding draft helps the part to release. Most parts or applications require a minimum of 1/2 to 1 degree, however 11/2 to 2 degrees is widely accepted as the norm.

HOLES ENHANCE PART FUNCTIONALITY AND REDUCE WEIGHT

Holes can be added to a part for functionality or to reduce overall part weight (coring). Core pins are typically used to form a hole, preventing the molten plastic from filling in that space. Through holes go all the way through a part. Blind holes do not completely go through a part. Core pins for a blind hole are only supported by one end, so there is a greater degree of difficulty in forming them without defect. Forming holes can lead to defects or have a negative impact on aesthetics. Since the molten plastic flows around the core pin, it can leave a weld line (which may be visible and/or be weaker than the remainder of the part).

The depth of a blind hole should be about two times the diameter of the core pin for small pins (less than 3/16") and four times the diameter of the core pin for pins greater than 3/16".
Distance from the edge of a hole to a vertical surface (edge or part or rib) or another hole should be at least two times the thickness of the part or at least the diameter of the core pin (hole).

Holes created in the direction of the opening/closing of the mold or parallel to the parting line are relatively easy to produce. Holes at different angles can be created, but may require special action in the mold utilizing core pulls or cams which can have significant cost impacts.

BOSSES AID IN ASSEMBLY AND MOUNTING

Bosses can be added to the part design for assembly, locating, or mounting of a part. Improper placement of a boss leads to uneven wall thickness and can have a negative impact on the aesthetics, shrinking, or strength of a part.

Wall thickness around a boss feature should be 55%–65% of the nominal wall thickness for thin walls (less than 1/8") or around 40% of the nominal wall thickness if greater than 1/8"
Boss height should be no more than 2 1/2 times the diameter of a hole in the boss

RIBS ENHANCE PART STRENGTH AND STABILITY

Ribs can be added to parts to add rigidity or stiffness. Adding ribs allows for a part to increase strength and bear a higher load. Ribs too have recommended guidelines to maximize functionality and minimize defects.

Rib thickness should be less than the wall thickness. Recommended thickness is 60% to 80% of the nominal wall.
Adding more ribs adds more strength or stiffness to a part. It is better to add more ribs than make larger or thicker ribs.
Ribs should be spaced at least two times the nominal wall thickness from one another.
Rib height should be less than three times the nominal wall thickness of the part.
If a thick rib is required, the center of the rib should be cored (cut out) to allow for uniform wall thickness.

ADDING A RADIUS REDUCES STRESS ON CORNERS

Radii should be added to angles to prevent sharp corners. Corners can lead to stresses, limit material flow, and often reduce part strength.

Inside radius of a corner should be at least half of the wall thickness
Outside radius of a corner should be equal to the part thickness plus the inside radius
A radius being added to a boss or rib should be 1/4 of the part thickness, no smaller than .015

Material selection and processing conditions are equally important factors in the proper design for a plastic injection molded component or part.

We understand that initially, material selection may seem overwhelming since there are so many materials to choose from. You can rest easy knowing that API has partnered with resin suppliers for over 60 years and has a multitude of experience in manufacturing plastic parts with even the most difficult-to-process resins.

ENGINEERING FEATURES USED

1. Rib

2. Screw boss

3. Heat stake

4. Doghose

5. Locators

RIB

Ribs increase the bending stiffness of a part. Without ribs, the thickness has to be increased to increase the bending stiffness. Adding ribs increases the moment of inertia, which increases the bending stiffness. Bending stiffness = E (Young's Modulus) x I (Moment of Inertia). The rib thickness should be less than the wall thickness-to keep sinking to a minimum. The thickness ranges from 40 to 60 % of the material thickness. In addition, the rib should be attached to the base with generous radiusing at the corners. They are thinner than primary walls and are used to support these walls, as well as bosses, by running perpendicular to these structures. Ribs are often used to replace thick wall sections to avoid sink marks, warp, and voids.

SCREW BOSS

Bosses are used for the purpose of registration of mating parts or for attaching fasteners such as screws or accepting threaded inserts (molded-in, press-fitted, ultrasonically or thermally inserted).

The wall thicknesses should be less than 60 % of nominal wall to minimize sinking. However, if the boss is not in a visible area, then the wall thickness can be increased to allow for increased stresses imposed by self-tapping screws. screw boss its a engineering feature which have thread in so the screw can get insrted and hold its place tightly so the two part remain assebled. screw boss used to asemble two component with the help of screw.

HEAT STAKE

Heat stakes ate generally screw boss line structure without tread in it used to join to part each other by thermal staking. heate stake is go trough the conter part from its parent part and at the tip its heated so it can weld over the conter part and these two parts are get assembled with each other. ther is no such a design gudlines for the heat stakes but yes design it with the

DOGHOUSE

Dog house is an engineering feature used in plastic trim design. Dog houses are used as supporting feature. Sometimes other engineering features like snaps; locators etc. are mounded on them to increase their
strength.

Design guidlines

Wall thickness = 0.70 x Thickness of the plastic material
Fillet on the inner side = 0.25 x Thickness of the plastic material
Fillet on the outer side = 1.25 x Thickness of the plastic material
Fillet on the coring edges = 0.25 x Thickness of the plastic material
Coring thickness = 0.40 x Thickness of the plastic material
Draft angle 2deg to 3deg

LOCATORES

A 2-way locating pin restricts motion along 1 axis (or 2 degrees of Freedom), like a round pin in a slot. Likewise, a 4-way pin restricts 4 degrees of freedom along 2 axes. A round locating pin located concentrically in a hole is a common application of a 4-way pin, and helps to further secure the piece.

TOOLINNG AXIS / TOOLING DIRECTION

Tooling axis is a direction of mould opening and closing, in this part we used Y component as a Tooling direction for 3 part except the door arm rest because in this input is of the door arm rest is complex part it is not manufectured in one direction and we have to add to meany side core direction which will make the mould more costly. so we have to just inform the class a designer all the things.

the assembly in going to be in Y direction and it will make easy to create the enginnering features design

CLASS A SURFACE and their respective Draft analysis

1. MAP POCKET UPPER

DRAFT ANALYSIS

2.MAP POCKET LOWER WITH BOTTLE HOLDER

DRAFT ANALYSIS

As we done the tooling direction as a y component some area of the map pocket is not cleared with this tooling axis or this is not even cleared with another tooling direction.

Minimum draft angle present at this area

minimum draft angle present at this area is -1.59 degree

3. DOOR ARM REST

DRAFT ANYLYSIS

From main tooling Axis

Side core Direction

4. LOWER SUBSTRAIT

DRAFT ANALYSIS

After performing draft analysis if all the class a surface.

Creation of Class B surface

to create class B surface refer the thickness from the master section and it is 2.5mm.

1. Map pocket upper CLASS B

2. Map Pocket with Bottle hodler CLASS B

3. DOOR ARM REST CLASS B

4. LOWER SUBSTRAIT CLASS B

CLASS C SURFACE CREATION

To create class c surface extract the edges to create the class, after extracting the edges of class a surface sweep the edges along the tiooling direction with 3 degree agle or some withe using the class a as reference surface with 90 degree.

1. Map Pocket upper Class C surface

2. Map pocket with Bottle Holder class C surface

3. Door Arm rest Class C surface

4. Lower Substrait Class C surface

Close Surface

1. Lower Substrain

2. Map Pocket upper

3. Map Pocket Bottle Holder

4. Bottle holder map pocket

CREATION OF ENGINNERING FEATURE

1. HEATE STAKE

TO create heate stake refered master section inner Diamerter is 5 mm and Outer radius is 7 mm.

heat stake sketch

Support Rib sketch

2. 4 way locator

i created locator with the doghouse because the hight is to much por a bare 4 way locator and their is also chance to breake the locatore if it is to high. an it wili aslo create sink marks or the locator ir not manufactures properly for that much hight.

locator sketch