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Revision as of 10:53, 22 September 2008

Executive Summary

For the past three weeks, team 11 has been analyzing the Wheely King RC car made by Hobby Products International. Our research is done in order to improve on the current design and make the car significantly better at Rock Crawling. Rock Crawling is an upcoming sport, and our group feels that with the Wheely Kings transformation into a Rock Crawler, a significant profit can be made.

The Wheely King is a 1/12 replica, having many intricate parts, and while having most of the weight in the rear, the car is designed to raise up on its two rear wheels. After analyzing the gears, a ratio of 23:1 was calculated, showing that the car is initially designed for more acceleration than torque and a below average top speed (18 mph). Through DFMA analysis and DFX analysis we found..........*****Zahoor, write a little sentence or two here, say that we found many parts that could be produced as one. Keep in mind that you are talking to an executive, so do not get too technical....... Through these findings, many design changes are possible to make the car perform to the consumers desired needs. Here is our list of recommendations:

Manufacture ..(Ricci, enter 2 or 3 parts here)... out of metal instead of plastic. The stronger parts will make the product more durable and capable of withstanding large torques.

Reduce the gear ratio to increase the amount of torque the car produces. Increasing the size of the pinion gear does not require any new parts other than the gear its self and can reduce the gear ratio to 10:1. This will dramatically improve the performance of the car. High torque is essential in rock crawling, so overlooking acceleration and top speed is justified.

Zahoor...... put your input on the dfx stuff here. I.e. if you make these 5 parts into 1, it will save lots of money.....

Stakeholder/Customer Needs

There are a few stakeholders that need to be considered when designing and manufacturing a Nitro RC car. First, raw material users in the company that provide the parts made of plastics, metal and rubber. The design of the parts should not be too complicated that injection molds are adequate for the scale of part. If parts are small, it may be difficult to make an accurate mold of an important small part. With design for manufacturing in mind as well, there should not be too many different parts to be molded making it easier on component producers. Next in mind are those who assemble the cars. The design of the RC car must be easy because there are many parts. The parts cannot be too hard to assemble together because of positioning or the size or placement of necessary fasteners. Again, similar parts are important for assemblers because it may be hard to distinguish very similar parts in assembly that may make a big difference if assembled to wrong way. Finally, the end product is important to the customers who buy the RC car. Since we are considering an off-road RC car, the product has to be durable through a significant lifespan. The car has to be built for off-road rock crawling and tricky terrain. The car also needs to be easy to fix, modify or replace parts if broken.

Product Use and Function

Our particular product is a 4x4 remote control truck Wheeley King. It is an entry truck for those interested in off road RC. The car is used and designed to crawls rocks and scale inclines with tricky terrain. These cars are not built for speed. They should be built to be durable because of the tough terrain it will be used on and should be durable for novice operator who are not as skilled and may damage the truck. RC cars need to be built to be easily modified for improvement if someone chooses to improve the performance of their car or in the event of failure in the truck.

The RC truck runs off of a rechargeable battery. The battery supplies a Sturn motor. The motor is contorlled through a remote control the user operates. Controls for speed of the motor and turning through the servo on the truck are on the remote control. The motor is geared down to provide more torque to the tires so that the motor can handle the tough forces that an off-road RC car may encounter. Power is distributed to front and rear wheels, making the car 4 wheel drive. Differentials located on front and rear axles allow for powered turns and more power supply to a slipping wheel. The car is designed with a wide wheel base to guard against rolling. The wheel base also twists and has shocks to adapt to rough terrain to allow for reasonable traction on many types of uneven surfaces.

Parts Table

Notes:

Masses omitted for non-vehicle components (i.e. radio transmitter, battery charger, included tools, etc.)

Part #	Qty	Description	Material (Man. Process)	Weight (g)	Picture
1144	1	Saturn Motor 27T (540 Type)	Multiple (Sub-assembly)	234.2
2029	1	HPI Ni-Cd Battery (7.2V, 1500mAh)	Multiple (Sub-assembly)	314.0
3062	4	Classic King Wheel (Chrome)	Plastic (Cast)	24.3
4894	4	Mud Thrasher Tires	Rubber(Molded)	214.3
6122	10	Body Pin (Medium)	Steel(Bent)	0.4
6125	4	Super Star Washer Set	Plastic(Cast)	0.2
6589	2	Shock Spring (13.5x80x1.1x18)	Steel(Bent)	6.9
6816	6	Silicon O-Ring (S10)	Rubber(Cast)	<0.1
6819	5	Silicon O-Ring (P3)	Rubber(Cast)	<0.1
6878	2	Shock Shaft 3x61mm	Steel(Threaded Rod)	4.5
6921	1	Pinion Gear (21 tooth, 48 pitch)	Steel(Cast)	3.5
6990	1	Spur Gear (90 tooth, 48 pitch)	Plastic(Cast)	3.6
7774	1	Mini GT-1 Painted Body	Plastic(Vacuum Formed)	85.0
80550	1	HPI TF-1 Transmitter	Multiple (Sub-assembly)	-
80556	1	HPI RF-1 Receiver	Multiple (Sub-assembly)	23.2
80559	1	HPI SF-1 Servo	Multiple (Sub-assembly)	35.5
80590	1	HPI Jolt+R Electronic Speed Controller	Multiple (Sub-assembly)	17.4
85250	2	Axle/Differential Case Set (Front/Rear)	Plastic (Cast)	37.9
85251	1	Center Gear Box	Plastic (Sub-assembly)	79.6
85252	1	Hub Carrier Set (Right/Left)	Plastic (Sub-assembly)	5.8
85253	2	Shock Body Set	Plastic (Sub-assembly)	14.4
85254	1	Main Chassis Set	Plastic (Cast)	42.0
85255	1	Bumper/Roll Bar Set	Plastic (Cast)	6.6
85256	1	Shock Parts/Shock Tower Set	Plastic (Sub-assembly)	7.6
85257	1	Suspension Rod Set	Plastic (Cast)	6.4
85258	1	Universal Center Drive Set	Plastic (Sub-assembly)	7.4	100px]]
85259	1	Drive Gear Set	Plastic (Sub-assembly)	7.4
85260	1	Servo Saver/Pivot Ball Set	Steel (Sub-assembly)	6.9
85261	1	Battery Box Set	Plastic (Molded)	43.4
85262	1	Rod Brace	Plastic (Cast)	9.8
85263	1	Arm Rod/Steering Rod Set	Plastic (Cast)	4.7
86094	6	Screw Shaft (M4x2x12mm)	Steel(Threaded rod)	2.7
86810	1	Gear Shaft (5x6x29mm)	Steel (Rod)	2.3
86812	1	Drive Shaft (6x32mm)	Steel (Rod)	2.5
86813	1	Drive Shaft (6x82mm)	Steel (Rod)	12.1
86815	1	Drive Shaft (6x43mm)	Steel (Rod)	4.2
86816	1	Thread Shaft (M3x102mm)	Steel (Threaded rod)	7.3
86818	1	Motor Plate (2.5mm)	Alum. (Stamped)	19.0
86819	1	Flanged Shaft 3x13mm	Steel (Cast)	2.1
87600	1	Differential Gear Set	Steel (Sub-assembly)	32.2
87601	2	Sport Shock Set (77-117mm)	Multiple (Sub-assembly)	20.2
9014	1	Overnight Charger for 7.2V Ni-Cd Batt.	Multiple (Sub-assembly)	-
A431	1	Diff Case	Plastic (Molded)	13.3
A549	2	Axle 5x40mm	Steel (Cast and threaded)	6.7
A850	1	Diff Bevel Gear Set	Steel (Cast)	4.0
A855	1	Diff Final Gear Set (P1x38T/P1x13T)	Plastic (Sub-assembly)	3.5
B022	2	Ball Bearing (5x11x4mm)	Steel (sub-assembly)	1.5
B030	2	Ball Bearing (10x15x4mm)	Steel (Sub-assembly)	2.0
Z150	1	Antenna Pipe	Plastic (Sub-assembly)	2.6
Z224	10	Washer (M3x8mm)	Steel (Stamped)	<0.1
Z242	20	E Clip (2mm)	Steel (Stamped)	<0.1
Z243	10	E Clip (3mm)	Steel (Stamped)	<0.1
Z244	10	E Clip (4mm)	Steel (Stamped)	0.1
Z264	10	Pin (2x10mm)	Steel (Rod)	0.2
Z281	4	Step Screw (M3x12mm)	Steel (Thread-rolled rod)	1.1
Z290	4	Step Screw (M4x15mm)	Steel (Thread-rolled rod)	2.3
Z488	6	Tp. Flanged Screw (M2.6x12mm)	Steel (Thread-rolled rod)	0.5
Z517	10	Binder Head Screw (M3x8mm)	Steel (Thread-rolled rod)	0.4
Z541	6	Cap Head Screw (M3x6mm)	Steel (Thread-rolled rod)	0.4
Z561	6	Tp. Flanged Screw (M3x10mm)	Steel (Thread-rolled rod)	0.6
Z567	10	Tp. Binder Head Screw (M3x10mm)	Steel (Thread-rolled rod)	0.6
Z569	10	Tp. Binder Head Screw (M3x15mm)	Steel (Thread-rolled rod)	0.8
Z571	6	Tp. Binder Head Screw (M3x20mm)	Steel (Thread-rolled rod)	1.0
Z684	4	Flanged Lock Nut (M4)	Steel (Cast)	1.3
Z700	6	Set Screw (M3x3mm)	Steel (Thread-rolled rod)	<0.1
Z852	10	Washer (5x7x0.3mm)	Steel	0.1
Z892	10	Washer (5x7x0.2mm)	Steel (Stamped)	0.1
Z901	1	Allen Wrench 1.5mm	Steel (Bent extrusion)	-
Z903	1	Allen Wrench 2.5mm	Steel (Bent extrusion)	-
Z904	1	Allen Wrench 2.0mm	Steel (Bent extrusion)	-
Z950	1	Cross Wrench	Cast (Alum.)	-

Design for Manufacturing and Assembly (DFMA)

Failure Modes and Effects Analysis (FMEA)

Design for Environment (DFE)

When designing a product, it is important to take into account the effects the product may have on the environment in the production phase and product use phase. Engineers use a process known as Life Cycle Assessment (LCA) to find processes or factors throughout the products life that is potentially damaging to the environment. Using table below, we have performed an Econmic Input-Output Life Cycle Assessment (EIO-LCA) for our RC truck. The table displays estimates of green house gas releases from the Doll, toy, and game manufacturing sector of the market.

From the table, we performed an order of magnitude estimation of metric tons of carbon-dioxide use in the production phase of an RC car. For our product, the cost of the truck was $200. The table is based on $1,000,000 of production of product. Seeing that 646 MT-CO2 is produced during produciton of toys, this yields about 0.1292 metric tons of CO2 for every RC truck produced. The largest sector that has an environmental impact during the use of our product is power generation and supply since the battery of the truck needs to be recharged. By looking at the power generation and supply sector, we found that this sector produces 9530 MTCO2. The battery for the crawler has a charge rate of 1500 mAh. Using this information, we have determined that that batter uses 30 watts every time it is recharged for the specified 6 hours. The following equaiton illustrates the amount of money it takes to create the energy needed to charge the battery throughout the truck's estimated 10 year lifespan.

$0.10/kWh*(0.03 kWh)*(6 hrs/day)*(100 days/year)*(10 years) = $18

This equation gives us the proportion of the power generation and supply sector that is dedicated to one of our trucks throughout its lifespan. From all of the information gathered, we determined that 0.17154 MTCO2 is produced in the use phase of an RC truck. The total combined amount of MTCO2 is approximately 0.3, which yields a $60 CO2 tax for one RC truck.

Looking at the table for the 1997 detailed item output from the Bureau of Economic Analysis, RC trucks do not make up a significant amount of the Doll, toy, and game manufacturing sector. This sector does in fact contain our product, but only about 25% of the sector is representative of our product overall. The results that we have obtained through our initial analysis seem credible, but our confidence on how accurate our use phase results are depends on the user. We assumed that the person who would buy a $200 RC rock crawler would be an enthusiastic user and would fresquently use the product. More in depth analysis would be necessary to be extremely confident with our results, but as a first pass, these results seem reasonable.

	Sector	GWP MTCO2E	CO2 MTCO2E	CH4 MTCO2E	N2O MTCO2E	CFCs MTCO2E
221100	Power generation and supply	205	203	0	0	2.47
484000	Truck transportation	49.0	48.3	0.075	0.674	0
3221A0	Paper and paperboard mills	48.7	48.7	0	0	0
339930	Doll, toy, and game manufacturing	35.3	35.3	0	0	0
325211	Plastics material and resin manufacturing	29.4	29.4	0	0	0
562000	Waste management and remediation services	23.6	3.73	19.9	0.029	0
211000	Oil and gas extraction	20.7	3.47	17.2	0	0
325190	Other basic organic chemical manufacturing	18.1	12.4	0	5.64	0
324110	Petroleum refineries	14.2	14.1	0.079	0	0
331111	Iron and steel mills	13.5	13.5	0	0	0
	Total for all sectors	646	555	57.4	20.6	12.8

Mechanical Analysis

Process

describe your team process for coordinating and completing all tasks

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