Keg tap

From DDL Wiki

(Difference between revisions)

Jump to: navigation, search

Revision as of 19:06, 20 September 2009

1 Executive Summary
2 Major Stakeholders and Product Needs
3 Usage
4 Bill of Materials
- 4.1 Keg Tap Components
- 4.2 Assembly Diagrams
5 Mechanical Function
6 Design for Manufacturing and Assembly (DFMA)
7 Failure Modes and Effects Analysis (FMEA)
8 Design for Environment (DFE)
9 Mechanical Analysis
10 Team Member Roles
11 References

Executive Summary

Describes key findings and recommendations

Major Stakeholders and Product Needs

Identify major post-production stakeholders and list major product needs for each

Usage

Document in detail how the product is used, step by step, and summarize findings from your user studies.

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Bill of Materials

Also identify standard purchase parts.

Keg Tap Components

Part Number	Name	QTY	Weight (oz)	Function	Material	Manufacturing Process	Image
1	Black Ball	1	1	Grip for pumping	Plastic	Injection molding
2	Plunger	1	4.3	Forces air into casing	Stainless Steel	Extrusion, machined threads
2.1	Plunger Disc	1	0.5	Air tight	Brass	Extrusion, drilled holes	--
3	Plunger O-ring	1	0.05	Seal	Rubber	Injection molding
4	Cylindrical Plunger Casing	1	6.3	Pressure for pumping	Stainless Steel	Extrusion, machined threads
5	Cylindrical Top	1	1.7	Encloses plunger in casing	Stainless Steel	Extrusion, lathe, machined threads
6	Plunger Spring	1	0.1	Prevents plunger from getting stuck	Stainless Steel	Extrusion, coiled
7	Center Cylinder	1	6.8	Separates air input from beer output	Stainless Steel	Extrusion, mill, lathe, drilled holes, machined threads
8	Center Cylinder O-ring	1	0.05	Seal	Rubber	Injection molding
9	Lever	1	4.1	Attaches tap to keg	Steel	Cast, machined threads
10	Lever Casing	1	0.5	Provides grip for user to pull lever up	Plastic	Injection molding
11	White Cap	1	0.1	Prevents nut from potentially falling off	Plastic	Injection molding
12	Lever spring	1	0.1	Provides compression that enables lever to lock in place	Stainless steel	Extrusion, coiled
13	Center Rod	1	0.5	Locks lever into machined groove on base	Brass?	Extrusion, machined threads
14	Nut	1	0.05	Attaches center rod to lever casing	Steel	Machined
15	Washer	1	0.05	Distributes force of nut	Steel	Stamped
16	Lever Pin	1	0.2	Holds lever on base	Steel	Extrusion, machined
17	Base	1	7.2	Attaches to keg	Steel	(Sand) cast
18	Base O-ring	1	0.1	Seal	Rubber	Injection molding
19	Hose	1	2.7	Transfers beer from keg to cup	Plastic	Extrusion
19.1	Connector	1	--	Connects hose to center cylinder	Brass?	Machined	--
19.2	Spout	1	--	Connects hose to nozzle	Plastic	Injection molding	--
20	Nozzle Sub-assembly	1	0.4	Releases beer from hose	Plastic	Injection molding
20.1	Handle	1	--	Provides leverage to compress the spring, opening the seal and releasing beer	Plastic	Injection molding	--
20.2	White Plastic Center	1	--	Connects nozzle handle to the cap seal	Plastic	Injection molding	--
20.3	Spring	1	--	Keeps handle down when nozzle not in use	Steel	Extrusion, coiled	--
20.4	Hard Plastic Cap	1	--	Attaches lever to nozzle base	Plastic	Injection molding	--
21	Nozzle Seal	1	--	Prevents beer from exiting nozzle until handle is lifted	Rubber	Thermoforming

Assembly Diagrams

Include pictures of the assembly with all components labeled

Mechanical Function

Document how the system functions mechanically

Design for Manufacturing and Assembly (DFMA)

Highlight findings and opportunities for improvement, identifying where our competitor has followed guidelines and made good choices.
In particular, are there opportunities to improve manufacturability and make a competing product cheaper? Identify where material and process choices are appropriate or inappropriate for expected production volume.

This particular keg tap consists of 26 distinct parts. The majority of the metal pieces are made from stainless steel, with the exception of three interior components that are made from brass. The reasons for making a few pieces brass are unclear; one possible improvement to the keg tap could be standardizing materials and using stainless steel for all the metal components.

The non-metal components are made from plastic and rubber. There are four o-rings in the keg tap, all of which are different sizes. This is a potential problem for consumers. The tap is manufactured so the user can take it apart, and it would not work correctly if the o-rings were mixed up and placed in the wrong locations when reassembled. Also, o-ring fatigue is one of the most likely causes of failure; if users are replacing o-rings somewhat regularly, it would be convenient to only need to order one standard size.

All of the metal components are shaped using a deformation process except for the base and lever, which are cast. Casting is a logical manufacturing choice for the base because of its relatively complex shape. The other main metal parts are extruded, then machined. Machining includes removing material with a lathe or milling machine, drilling holes, cutting threads, and grinding down sharp edges. The amount of machining involved in the manufacturing process is acceptable for this product because it is intended for medium volume production. If the target market increased in size or changed demographics, the current manufacturing processes would have to be reevaluated. An increase in market size would make machining individual parts infeasible. This problem could be solved by either redesigning the tap to have less components, or switching to a process more suitable to high volume production, such as metal injection molding. A change in market demographics, such as a shift in sales from middle-aged beer connoisseurs to college students, would call for a change in the price of the keg tap. This could be achieved by switching to a casting process for more parts; the overall aesthetics might not be as pleasing, but machining costs would go down.

All parts are joined by threads or snapped on (o-rings). This saves machine cost in manufacturing, but may add labor cost. The current joining methods are good for the consumer because you can take the tap apart to clean it and replace parts if need be. A common failure mode may be o-ring fatigue; these parts could easily be replaced instead of buying a whole new tap.

DFM minimize part count standardize components standardize design features keep design simple multifunctional parts ease of fabrication avoid tight tolerances minimize secondary & finishing operations

DFA minimize part count minimize assembly surfaces mistake-proof minimize fasteners

Failure Modes and Effects Analysis (FMEA)

Highlight findings and opportunities for improvement, indentifying where our competitor has followed guidelines and made good choices.
In particular, are there important failure modes that should be considered in a redesign or a new design? Focus on use phase, rather than manufacturing.

Part #	Item	Function	Failure Mode	Effects of Failure	S	Cause of Failure	O	Design Controls	D	RPN	Recommended Actions
1	Black Ball	Grip for Pumping	Could be Unscrewed and Lost	Uncomfortable Pumping	4	Unaware Users	1	Make sure the ball is screwed on tightly	1	4	Apply Loctite
2	Plunger	Forces Air into Keg	This part is very robust. Cannot foresee any failure modes.	---	-	---	-	---	-	-	---
3	Plunger Disc	Air Tight	This part is very robust. Cannot foresee any failure modes.	---	-	---	-	---	-	-	---
3.1	O-Ring	Seal	O-ring becomes hardened	Loss of air tight seal for pressurizing keg	3	Repeated use and time	5	Oil the o-ring	5	75	Sell spare parts
4	Cylindrical Plunger Casing	Supply Keg with Pressure	Dent in the casing, burs, scratches, rust on the inside of the casing	Plunger cannot be moved inside the case, o-ring gets torn up	7	Misuse, Dropping the tap	1	All these pieces are robust enough	1	7	None
5	Cylindrical Top	Encloses Plunger in Casing	Top comes unscrewed	Cannot pressurize keg	1	Human tampering	4	Check that it is screwed on tightly	2	8	None, gluing these threads makes disassembly harder
6	Plunger Spring	Prevents Plunger from Getting Stuck	Breaks	Plunger, though unlikely, may get stuck at top of casing	7	Misuse or fatigue	1	Make sure spring can handle forces	1	7	Sell spare parts
7	Center Cylinder	Separates Air Input from Beer Output	1)Leaks beer at the connection point with hose 2)Creates turbulence in beer flow	1)Loss of beer 2)Foamy beer	5	1)Sealant on threads is old 2)Manufacturing	4	1)Check that their are no leaks 2)Their Design	1	20	1)None 2)Look into some other way to transition into tubing
7.1	O-Ring	Seal	O-ring becomes hardened	Loss of air tight seal for pressurizing keg	3	Repeated use and time	5	Oil the o-ring	5	75	Sell spare parts
8	Lever	Attaches Tap and Keg allowing the flow of beer	This part is very robust. Cannot foresee any failure modes.	---	-	---	-	---	-	-	---
8.1	Lever Casing	Grip for user	Breaks	Unable to attach tap to keg	7	Ridiculous Misuse	2	Make sure the part is strong enough	1	14	None
8.2	White Cap	Aesthetics	Could break or get lost	None	1	Misuse or overuse	2	Check this fit	1	2	None
8.3	Lever Spring	Helps lock tap in two certain positions	Impact fatigue	Unable to lock tap into open position on keg	7	User misuse	2	Make sure spring can handle forces	3	42	Brainstorm new ways to lock tap
8.4	Center Rod	Helps hold handle together	This part is very robust. Cannot foresee any failure modes.	---	-	---	-	---	-	-	---
8.5	Nut	Helps hold handle together	Could come unscrewed	Unable to use tap		Repeated use		Make sure it is screwed on the whole way			None
8.6	Washer	Helps hold handle together	Cannot foresee any failure modes
9	Lever Pin	Attaches the lever to the base and acts as a pivot point for the lever	No foreseen failure modes.
10	Base	Attaches to Keg	Threads become crooked	Unable to connect tap to keg		Terrible misuse		Threads are very robust			Sell spare parts
10.1	O-Ring	Seal	O-ring becomes hardened	Loss of air tight seal for pressurizing keg		Repeated use and time		Oil the o-ring			Sell spare parts
11	Hose	Transfers Beer from Tap to Cup	1)Hole 2)Kink	1)Beer is lost 2)Beer cannot reach its destination		1)Not taking care of tap 2)Jokes		Make sure the tubing is the right kind			None
12	Nozzle	Releases Beer from Hose	No foreseen failure mode
12.1	Handle	Allows the user to start and stop the flow of beer	Deform/Break	Beer would not be allowed to come out the nozzle		Pushing the handle past where it should be		Use thick enough plastic			Sell spare parts
12.2	White Plastic Center	Connects nozzle handle to cap seal	Connection point to nozzle handle breaks	Beer can not come out of nozzle		Pushing the handle past where it should be		Test to make sure it operates the way it should			Sell spare parts, look for a possible redesign
12.3	Spring	Apply extra force to keep the pressurized beer from coming out of the keg	No foreseen failure modes
12.4	Cap Seal	Blocks the flow from leaving the hose	Surface fatigue wear	Beer would leak through and leave the nozzle		Repeated use		Make sure the rubber used can withstand many cycles			Sell spare parts
12.5	Hard Plastic Cap	Connects the Handle to the nozzle	Fracture	Nozzle/Handle would not be able to function		Over tightening the cap onto the nozzle		Tighten cap enough so users do not have to			Sell spare parts

Design for Environment (DFE)

Highlight findings and opportunities for improvement, indentifying where our competitor has followed guidelines and made good choices.
In particular, if Congress were to pass a tax on CO2, would this have a significant impact on the cost of production or use of the product?

Manufacturing

Greenhouse Gas Emissions

When an additional $1 million dollars is spent in the Miscellaneous fabricated metal product manufacturing sector, greenhouse gas emissions rise by approximately 796 metric tons of CO2 Equivalent (MTCO2E). The data shows that the majority of the gases are produced by power generation and supply, iron and steel mills, and transportation. The actual sector that produces the tap only produces 42.6 MTCO2E, which is small considering the amount released in other sectors.

Toxic Releases

An additional $1 million dollars spent in the sector for keg taps results in a rise in total toxic releases of 1590kg. The primary contributors to these releases are mining of: copper, nickel, lead, and zinc gold, silver, and other metal ore mining. The Miscellaneous fabricated metal product manufacturing sector only amounts to a 57.1 kg increase in toxic releases.

Use

Using the template of Professor Michalek's "EIO-LCA example: coffeemaker" we did a comparison of the emissions associated with the use of the product versus the manufacturing of it. Since the keg tap itself is manually operated the power input is not applicable, but there are other products that are used with the keg tap. Foremost, is beer from a keg and we assumed that this product would be used to the extremes, like a fraternity would use it. We decided this too see what the maximum impact would be of using 520 kegs over a 5 year lifetime window. Secondly, solo cups are a necessity so we included them as well, assuming 100 cups used per keg.

Based on the data above, it is clear that the manufacturing of our tap has next to no environmental impact compared to the manufacturing of plastic cups and especially to the brewing process.

End of life

Our product is composed of only metal and plastic, both of which can be recycled. So once our product can no longer perform as intended it can be recycled in a few ways. Some parts are almost impossible to break and can be used again as is and just reassembled with parts that needed to be replaced. The pieces that break can be melted down and reused in some way, whether they are plastic or metal.

DFE Conclusions

Based on the numbers provided in figure ## it would be wise for our group to emphasize on trying to reduce wasting beer because it is the largest component of greenhouse gas emissions associated with our product. A large amount of foam is produced in transport and distribution of the beer in a keg and it is normally thrown away. If we could reduce the foam created we could in turn reduce the environmental impact that our product is associated with.

Mechanical Analysis

There are 2 different mechanical analysis’ that we did on the keg + tap system. The first is how much pressure per pump increases in the keg, which in turn would increase the pressure in the hose. Second, since our system is composed of fluid flowing through tubes we can determine if it is flowing in a laminar or turbulent fashion.

Problem 1: Find the change in pressure per pump

Assume:

No pressure is lost in the system at all

Free Body Diagram:

Dimensions:

Solution:

Problem 2: Find out if the fluid flow in the tube is laminar or turbulent