Window blinds

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Revision as of 18:22, 3 February 2011

Executive Summary

Major Stakeholders

Customer – Customers include those individuals or parties who actually purchase the blinds to fulfill a purpose. What they might be looking for in a set of blinds can vary from style and color to functionality and efficiency. Should there be any problems with the original set of blinds, parts should be easily replaceable. For consumers, it is all about an attractive, low-cost, and easy-to-maintain product.

User – Users in most cases will not be limited to the customer. Depending on where the blinds are installed, there could be 1 user or 1,000 users. A user will expect the blinds to be effective, sturdy and durable, and easy to use and clean.

Installer – The installer could be the customer, but in some cases could also be a professional who is familiar with home product installations. Of utmost importance in this case will be the compatibility of the blinds with standard tools and the minimization of steps for assembly.

Retailer – The retailer will be the first major post-production stop for a new set of blinds. For retailers, it is necessary that blinds not only cater to consumer needs, but do so in a way that gives retailers an incentive to sell them. Specifically, there should be sufficient variety in size, color, etc. to capture the needs of most customers, the blinds should fit into packaging that is easy to handle, store and ship, and the wholesale cost should be low enough that the retailer can make a profit.

Product Use

Product

Assembly

Bill of Materials

Part Number	Name	Qty.	Weight (g)	Function	Material	Manufacturing Process
1	7/16 Screw	2	<1	Attach wall mount to wall	Aluminum	Heading, Thread Rolling (standard purchase part)
2	7/8 Screw	12	<1	Attach wall mount to wall	Aluminum	Heading, Thread Rolling (standard purchase part)
3	Wall Mount	2	7	Offers surface for blinds to rest on the wall	Plastic	Injection Molded
4	Mount Lock	2	<1	Keeps blinds in the mount	Plastic	Injection Molded
5	Optional Hold Down Bracket	2	<1	Holds blinds in fixed setting (down)	Plastic	Injection Molded
6	Knot Cover	2	<1	Covers the knots at the main string ends and offers the user a gripping location	Plastic	Injection Molded
7	Beads	2	<1	Allows user to set lowest blind setting	Plastic	Injection Molded
8	String Plugs	2	<1	Plugs the main string insertion hole	Plastic	Injection Molded
9	Ladder String	2	<1	Contains equally spaced rungs to hold blinds	Nylon	Weaving
10	Main String	2	3	Control mechanism for blind height	Nylon	Weaving
11	Blinds	49	7	Directly affects amount of light and privacy	Plastic	Extruding, Stamping
12	Bottom Bar	1	92	Contains excess ladder string, acts as a weight for lowering the blinds	Plastic	Extruding
13	Bottom Bar End	2	<1	Covers ends of bottom bar, has hole for optional hold down bracket	Plastic	Injection Molded
14	String Brace	2	<1	Fixes ladder string in place at the top of the blinds	Plastic	Injection Molded
15	Ladder String Stopper	4	<1	Gives ladder string a way to stay attached to the main frame	Aluminum	Extruding, Bending
16	Inner Rotating Rod	1	23	Holds main frame components in place, controls tilt of blinds	Aluminum	Extruding, Stamping
17	String Roller	2	<1	Provides a smooth surface for the main string to slide against	Aluminum	Extruding
18	Ladder String Holder	2	<1	Holds ladder string in place, allows for tilting	Plastic	Injection Molded
19	Main Frame	1	133	Holds both raising and tilting components	Plastic	Injection Molded
20	Lock Housing	1	<1	Holds the locking mechanism	Plastic	Injection Molded
21	Lock Housing Pin	1	<1	Fixes lock housing to main frame and acts as a holster for depressed locking gear	Aluminum	Extruding
22	Locking Gear	1	<1	Catches string when slid against it, acts as the stopping mechanism	Aluminum	Extruding
23	Locking Roller	1	<1	Provides a smooth surface for the main string to slide against	Aluminum	Extruding
24	Lock Plate	1	<1	Provides a smooth surface for the main string to slide against	Aluminum	Bending
25	Twisting Rod Connector	1	<1	Connects twisting rod to twisting rod hook	Plastic	Injection Molded
26	Twisting Rod Cap	1	<1	Closes the bottom end of the twisting rod	Plastic	Injection Molded
27	Twisting Rod	1	26	User control device, translates to blind tilt angle	Plastic	Injection Molded
28	Twisting Rod Casing	2	<1	Holds twisting gear and twisting screw in their proper locations, shaped to fit into main frame	Plastic	Injection Molded
29	Twisting Gear	1	<1	Holds inner rotating rod, and interacts with twisting screw	Plastic	Injection Molded
30	Twisting screw	1	<1	Converts user input turning to twisting gear rotations	Plastic	Injection Molded
31	Twisting Rod Hook	1	<1	Allows twisting rod to connect to twisting screw	Aluminum	Bending
32	Hook Sleeve	1	<1	Keeps twisting rod hook attached to twisting screw	Plastic	Extruding
33	Rivets	3	<1	Holds twisting rod container together and locking roller together	Aluminum	Casting (standard purchase part)
34	Rotating Rod Housing	2	<1	Holds the Rotating Rod and the Main String Roller	Plastic	Injection Molded

How the system functions mechanically

The packaged set of blinds can be split up into two separate phases: installation and use. During the installation phase the customer is supposed to install the wall mounts using the provided screws. Additionally the package provides an optional installation of the hold down mounts these mounts have pins that will hold the blinds in a lowered resting state. The hardware to install these mounts is included in the package. There are two ways for the customer to interact with the blinds after installation is complete.

The first way is to raise and lower the blinds according to preference. On the right side of the blinds there are two strings that can be pulled to disengage the lock or pulled to the right and released to reengage the lock. The locking mechanism consists of a gear that catches the string when it is released and pins it against another surface. The main string runs over a series of rollers in the main body, travel through the blinds and are tied off in the bottom bar. When the user pulls the string to adjust the height, the main string pulls or releases the bottom bar thereby raising or lowering the blinds.

The second way the customer can interact with the blinds is by controlling the tilt on the blinds by adjusting the twisting rod. By turning the rod clockwise the blinds rotate so that they are concave towards the customer. Rotating the rod counterclockwise produces an opposite effect. This is achieved through the translation of motion from the tilt rod to the inner rotating rod. When the twisting rod is turned, it turns a worm gear inside of the twisting rod casing. The worm gear turns a worm wheel that the inner rotating rod is attached to. On the rotating rod are two braces that can hold the ends of the ladder string. When the rotating rod turns, it makes one end of the ladder string pull up into the mainframe while releasing the other end. When this occurs, the blinds begin to tilt according to the customers input.

DFMA

The blinds that we dissected were cheaply purchased and because of this we know that they are massed produced. The assembly is relatively complicated with many interdependent working parts. After examining the manufacturing techniques used to produce the blinds we feel that the efficiency has been maximized. Most parts have been produced so that they can be used interchangeably, for example left and right parts do not matter. We saw that unnecessary material was removed from certain parts to reduce material usage and to make installation easier. We found that many parts snap together to make manufacturing time minimal and the same parts could be used for larger or smaller blinds. Minimal tools are required to manufacture and assemble these parts. Because these are inexpensive blinds that design was kept simple and fulfills its most basic purposes. The blinds use a lot of plastic parts and most of the plastic is the same. None of the parts manufactured seem to require tight tolerances.

Design for manufacturing guidelines

Minimize Part Count: Eliminate fasteners, part consolidation - only 3 rivets - wall mounts are interchangeable for left and right sides

Standardize Components: Take advantage of economies of scale & known component properties - wall mount had a lot of holes, reduced material, easy to install - many components come in pairs

Communize Product Line: Economies of scale and minimum training and equipment - parts snap together - larger blinds use similar parts

Standardize Design: Common dimensions for fewer tools and setups - only need rivet gun, bending machine

Keep Designs Simple: Simplest way to achieve needed functionality - easy access to screws

Multifunctional Parts: - wall mount can be left on right, many parts are interchangeable - lock house pin also supports lock gear

Ease of Fabrication: Choose materials easy to work with - product uses the same plastic material for many parts

Avoid Tight Tolerances: Causes exponential cost increases - no parts are machined

Take advantage of Special Process Properties: - wall mount, reduction of material

Design for Assembly guidelines

Use subassemblies: can be assembled and tested separately, can be outsource - not outsourced, but can be assembled in parallel

Mistake-Proof: unambiguous, unique assembly orientation - lock mechanism (roller, gear) are not dependent on orientation

Minimize Fasters: snap fits and part consolidation - there are a lot of snap fits - small sizes make it harder to assemble by hand