Laptop chill mat

From DDL Wiki

Executive Summary

Stakeholders Information

Usage

DFMA

Design for Manufacturing

The competitor’s product has been designed well with respect to manufacturability. The product has a low complexity as well as a part count that matches the level of complexity, as it has a good number of parts for its complexity. The most number of parts comes from the number of screws. Although could be lowered by changing from screws to a molded in, snap-fit feature, the screws allows for the part to be assembled easier, have an option to later open the part without breaking it, and keeps the mold simpler and cheaper.

Design for Assembly

Although the design for assembly can be improved on, most aspects of the design have been optimized to enable an easy, cheap assembly process. As for major improvements, the fan containment shell could be joined with the bottom body piece as one piece. There could be certain problems regarding the manufacturing process, but it would improve the design for assembly. In addition, the electric components including the fan and USB component, could be a subassembly that could be manufactured separately. The Logitech logo piece is unnecessary and just adds to the complexity of the assembly. Lastly, joining the felt to the bottom piece provides an assembly complexity as it may require multiple assembly directions or manual assembly. As for minor improvements, screws could be replaced with snap-fit designs and the screws necessary could be standardized. As for the current design, the elastic spacers between two parts are a useful inclusion for variable manufacturing tolerances. Another noteworthy design decision was the fan subassembly. The fan component consisted of a magnet, and it rested over the copper coils, which enables easy assembly without rotating shafts and additional components while being an effective motor. The general assembly process seems unambiguous and the assembly surfaces are kept to a decent minimum.

FMEA (Failure Mode and Effects Analysis)

Across the board, the detectability of failure modes for the device is very low, that is, anything that goes wrong with the device will be quickly and easily spotted by the user. The highest RPN value is associated with the mode of failure wherein the USB cord stops transmitting power due to damaged wires inside. This is a critical failure mode because it compromises the functionality of the whole device, the part is not easily replaceable, and USB wires are not typically very sturdy. To combat this potential failure, we propose a retractable USB cord, which would avoid situations where slack in the cord makes it susceptible to damage. Another major concern from the analysis above is the screws becoming loose with use over time. This can be easily repaired, and to make it even less of a concern, we could use screws which have common head sizes in the improved design iteration to allow for home repair.

Table

Failure Modes and Effects Analysis - Laptop Chill Pad
Items and Function	Failure Mode	Effects of Failure	Severity	Causes of Failure	Probability of Occurrence	Design Control	Detectability	RPN	Recommended Actions
Fan - cools laptop	Fan blades break off	Laptop heats up	6	Dent/Other Defect Causes Fan to Collide with Casing	1	Tolerance Testing on Fan/Casing	3	18	Keep Injection Mold Simple to Avoid Defects
Fan - cools laptop	Fan stops spinning	Laptop heats up	7	Fatigue, Loss of Power from Motor	1	Fatigue Testing of Fan	1	7	Choose Material to Meet Needs
USB - Provides Power	Disconnection	Loss of power to chill pad	2	Loose Port, Something Snags Cord	7	None	1	14	Entertain options for compact cord wrapping
	Broken inner wires	Loss of functionality	6	Damage to cord	2		3	36	None (Out of Designer Control)
	Bend on connector	Connector could break off inside laptop	7	Bumping Connector While Inside Port	2		1	14	None (Out of Designer Control)
	Power diverted elsewhere	Lower performance of chill pad	2	Too Much Usage from Programs	3		3	18	Keep Software to Low Power Usage Specs
Casing - Protects fan	Fan blades break off	Laptop heats up	6	Dent/Other Defect Causes Fan to Collide with Casing	1	Tolerance Testing on Fan/Casing	3	18	Keep Injection Mold Simple to Avoid Defects
Motor - Drives Fan	Fatigue	Stops rotating fan	6	Electrical Problem, Demagnetization	1	Cyclic Testing of Motor	3	18	Entertain Different Motor Configurations
Air Intake - Allows Air to Enter Through Bottom	Allowance of More than Air to Get Through Fan	Lower fan performance, Possible damage fan	3	Over-sized openings	3	Testing with Dust/Debris Under Chill Pad	2	18	Reduce Hole Size
Air Intake - Allows Air to Enter Through Bottom	Mechanism Holding USB Cord Breaks	No convenient storage of for USB Cord	3	Broken(Yielded) Tabs	3	Cyclic testing of tabs	2	18	Retractable USB Cord
Grill - Allows Air Through Top	Particles slipping through grill	Possible damage to fan	3	Over-sized openings, Damaged grill	2	Strength testing of grill	2	12	Change Angle of Grill, or Use Different Cooling Method
Screws - Holds Assembly Together	Loosening	Assembly falling apart	4	Overuse, Fatigue	2	Testing of regular use	3	24	None (Out of Designer Control)
Rubber stoppers - Stops the computer from slipping	Disconnects from grill	Laptop slips off chill pad							Put stronger grips on the rubber stopper
Rubber spacers - Pushes apart the top and bottom cover									Add more support to lessen the load on each spacer

DFE

Bill of Materials

The chill pad consists of five simple components: top cover, bottom cover, air intake, grill, and fan subassembly. The assembly is fairly straight forward. There are 16 parts we identified in the assembly. It consists mostly of plastic parts which were manufactured using different molding methods. Several metal screws were used to attach the components together. There are electrical components in the assembly that we did not disassemble such as the motor, switch and the USB connector. In the table below, the parts we identified are listed along with their properties and functions.

List of Components

Part Number	Part Name	Quantity	Weight (g)	Material	Manufacturing Process	Function	Part Image
1	Top Cover	1		Plastic	Molding	Connects to the top grill and bottom cover. Protects inner workings.	Top Cover
2	Top Grill	1		Plastic	Molding	Connects to the top cover. Protects the fan and allows fan blown air to go through.
3	Small Steel Screws	5		Steel	Molding	Connects the top cover to the bottom cover.	Screw
4	Rubber Screws	4	.25	Rubber	Molding	Connects the fan assembly to the top cover.	Rubber Screw
5	Fan Casing	1	15	Plastic	Molding	Connects to the top cover and the fan.
6	Fan	1	25	Plastic	Molding	Spins and blows air through the grill.
7	Motor	1		Copper, Plastic		Connects to the fan. Spins the fan.	Motor
8	Felt	1	40	Felt		Glued to the bottom cover. Provides soft interface between the user and product.
9	Bottom Cover	1	186	Plastic	Molding	Connects to the top cover and protects the inner workings. Provides a base for the product.	Bottom Cover
10	Air Intake	1	81	Plastic	Molding	Connects to the bottom cover. Allows air to flow into the chillpad.	Air Intake
11	Screws	3		Steel	Molding	Connects the air intake to the top cover.	Screw
12	Rubber Spacers	4	.25 each	Rubber	Molding	Pushes on the top and bottom cover to provide a space in between.
13	Removable Rubber Stoppers	2	12 each	Rubber	Molding	Connects to the top grill. Provides increased friction between the laptop and chillpad to keep it from moving.
14	USB Connector	1		Steel	Stamped	Connects the chillpad to the computer to draw power.
15	Switch	1		Plastic,	Molding	Allows the user to control the fan speeds.	Switch
16	Wires	1		Plastic, Copper		Connects the motor to the switch and then to the USB Connector.