Folding table

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Executive Summary

The initial documentation we have here is meant to be a resource for our expansion and improvement on the current product line of folding tables. After doing some short analyses on the life cycle and environmental impact of the table, we can then determine the proper areas that can implement innovative qualities. Our product is meant to be a valuable resource for consumers that either have very little space or need transformable affordable furniture or for the consumer that is on the go and needs something more portable than its counterpart. Using materials that are relatively inexpensive to manufacture, but are at the same time sturdy and lightweight the table is a must have for outside use. Similarly the plastic on top is stain proof and relatively scratch proof. Our documentation of the product was conducted after an expansive dissection of the table was done. We then created a catalog of all of the components the table is comprised of. Later we conducted a Design Analysis (DFMA) and a Failure Mode Effects Analysis (FMEA). These were done to determine any improvements that should be done and how we could do improve the products form and function. Our findings of the FMEA showed us that the table could benefit from a bit more simplicity, certain aspects of the unfolding mechanism seemed overly complicated and there were instances where two parts could have been merged into one part, which typically means more simplicity. Additionally, we conducted a EIO-LCA analysis of the table trying to find particular sources of environmental unfriendliness and what could have been improved upon that. Therefore we decided that our primary goal is to reduce product parts and focus on the environmental impact that manufacturing each of these parts has.

Stakeholders and Customer Needs

The importance of having a solidly built table that is easily transportable can be attributed to many situations. Main purposes could include camping, picnics, festivities, and outside events in general. There are various types of folding tables out there so it is hard to tell which would best work into our design. However, the use of each table relies heavily on what type of consumer would be using it. The table should be able to withstand a significant amount of force but does not need to be overly designed as most tables will normally not have a large amount of weight on it. For materials, the top is most likely going to remain some sort of plastic or reinforced composite such as fiberglass or carbon fiber.

Primary Stakeholders and concerns:

• The product must be relatively easy to carry, in a convenient way

• Must be resistant to rust and general wear and tear

• The table must serve its primary function, and support everything evenly

• The design of the table must result in a lightweight frame

• Table must be level and flat

• Since it is a folding design it must be able to fold and close without delay or difficulty


• Because the table can fold for storage it is easy for retailers to carry the item in their store

• The table is also light, therefore, making it possible for customers to carry them and handle them on their own without assistance

• The table will come fully assembled requiring no assembling

• The table will also be aesthetically pleasing as we will have optional lettering on the tables available or a graphic of choice

• Tables could be custom sized or fit

• Custom indented shapes could be fit onto the table (similar to the cup hole in an airplane fold down tray)


• The materials used must be cost efficient and sturdy

• Any excess material or waste should be able to be reused/recycled

• The parts of the table should be straightforward for assembly

• Materials and parts should be able to be found locally for ease of transport

Shipping and Transport:

• Table or the shipping box must be durable and sturdy to withstand any careless transportation mistakes.

• Materials must not rust if taken overseas, in case a package is broken or unsealed

How it Works

The folding table improves on a traditional table because, as its name implies, it can be folded up into an envelop of space much smaller than its space envelope when the legs are fully extended. For example our table is 60 in long x 27.5 in wide x 29 in high with the legs extended, but only 30 in long x 27.5 in wide x 3.25 in high with the legs folded in and the table folded in half. As explained earlier this advantage can be exploited all the way down the supply chain from manufacturer, retailer, down to the consumer. The table weighs 24.75 lbs.

                                                                           Figure 1 – Table with legs fully extended

                                                                           Figure 2 – Table with legs folded in and table folded in half

To fold the legs in to the center, there are two pin joints shown below in Figure 3. Moving the leg in towards the center will eventually move the middle bar in towards the underside of the table until both are completely flush with the under side of the table. Before this can happen, however, a lock must be removed.

                                                                           Figure 3 – Illustration of two pin joints

The lock mechanism is a metal ring that slides into a slot at a point in which it wraps around both legs. Thus when one attempts to move the outer leg inward, it can only move so far before being impeded by the ring.

Legs in the locked position
                                                                           Figure 4 – Legs in the locked position

To unlock the legs, the metal ring must be moved to the right slot where it no longer wraps around the outer leg. Consequently, the outer leg can now be moved in and start the folding process.

Legs in the unlocked position
                                                                           Figure 5 – Legs in the unlocked position

Now the legs can be moved in towards the center. As the legs move in, the middle bar moves down towards the underside of the table rotating on a pin joint.

                                                                           Figure 6 – Legs being folded

With the legs fully folded in, they must now be locked to ensure that they do not flop out again.

                                                                           Figure 7 – Legs folded

The lock is a flexible piece of plastic that the legs can be snapped into. They will not become unlocked without a pulling force, which would not happen except by someone intentionally pulling them out.

                                                                           Figure 8- Plastic leg lock

Now that the legs are locked into place, the table can be folded in half through the center pin join that runs through the entire width of the table. Because there is a pole to either side, the pole lies in double shear as shown below.

                                                                Figure 9 – Pin joint that allows table to fold 

Additional improvements:

• Better/popout handle

• Integrated chair, for when it is folded

• Magnetic closure or magnets to attach utensils and plates

• Stamps that could fit utensils or plates

• Transporting it in general, anything that could make it smaller

User Study:

After reading some reviews and talking to users, we have gathered that some of the largest issues with other tables is that they can be slightly uneven and eventually become dented on the top surface. Additionally, the largest complaint overall of this table and others is that the handle is very cumbersome. It almost seems like it was an afterthought, and was just molded into the top part of the table. Our group thinks that a proper handle would be more advantageous.

However, customers did like that the top folded, they claimed that this made it extremely easy to fit multiple tables in small places for example under a bed or in a closet. To remedy the denting issue, it is simply a means of choosing a harder plastic or finding a way that the top table part is not hollow, as we found out that it was after dissecting.

Bill of Materials

The Table Surface consists of two injection molded pieces of plastic bonded together. This was done using some sort of spot welding, ultrasonic welding, chemical joining, or friction welding. The areas joined, when cut through, showed solidity through the thickness without bubbles or gaps. There were slight discolorations in the seams near the edges of the material. This type of discoloration is indicative of plastic deformation, which can occur in the cooling after a high temperature joining method. This method yields a sandwich composite like panel with two face sheets and a relatively sparse shear web in between. This type of construction is extremely efficient in achieving high stiffness to weight. Show below is a cut away of the table surface.

Design For Analysis

The simple table exhibits relatively good characteristics for DFA. Most of the parts used to construct and support each side of the table are the same with the exception of one piece. There is a support leg which differs on one of the halves of the table from the other, but seeing as the rest of the connections to that part are the same on both sides, this does not greatly increase the complexity of assembling the table. Also, as previously described, many of the parts are riveted together which, for high volume production, is efficient, low-cost and decreases assembly time. For the parts which do not use rivets, bolts of the same thread size are used. This means that the same size washers can be used as well which simplifies the task of assembling the table. From this information, we can see the designers prioritized ease of assembly through use of uniform size connectors. Also, there is only one differing part between the two halves of the table.

DFA Summary

• Prioritized ease of assembly through standardization of part size

• Assembling of table is simple and opening is kept simple by using few moving parts

• Use of rivets decreased assembly time and cost

Design for Manufacturing

The folding table exhibits excellent DFM as it is very functional in design and has a minimal amount of parts while still fulfilling its purpose.

The legs of the table can be easily fabricated. First, a tube must be cut down to the proper length. Then the tubes must be bent according to the specs using a hydraulic pipe bender and holes are drilled where the rivets and bolts will be fit. Finally, the legs are painted to protect the metal. This is the best way to produce these parts unless the mechanism to support the table changes.

For the flat fold out supports, these may be stamped out of sheet metal and bent to the appropriate shape. The holes may be then drilled out accordingly. Using stamping for this process is an efficient and cost-effective way to produce these parts.

Finally, the table top is made of plastic. To do this, two pieces are created using injection molding. The parts are then glued together leaving a textured surface on the top and injection pins on the bottom where the part was pushed out of the mold. This is seemingly the best way to create the table surface as it is simple and is optimal as it is impossible to use less molds.

Tolerances for this part are relatively low. The only places where they may be somewhat important are where holes line up in separate components such that the bolts and rivets can be inserted and pieces properly joined.

A change which would slightly simplify manufacturing would be to change the configuration of the supporting exterior bars. To decrease the amount of different parts to be made, the two bars on the outer part of the table. The end of the first bar has two flaps approximately 1.5 inches apart from each other. The other part has two flaps approximately 1 inch apart. This could be simplified by having one flap on the right and the other off-centered, this way they would overlap and could be connected. Instead of making two different parts, one part would suffice.

Failure Mode and Effect Analysis

In brainstorming failure modes of the folding plastic top table, very few mechanical failures seemed reasonable to address. Under normal operation, tables like the one studied encounter low forces but must allow very little displacement in order to please customer need for stability. This leads to rigidity being the driving factor in the design, not necessarily strength. To attain the desired stability, the minimum factor of safety on the strength of the materials becomes very large. Due to this, there are few circumstances encountered in normal use that would load the table to mechanical failure. The one potential failure identified of this type was the most serious on our list despite having an RPN of only 80. This failure, very common amongst tables, chairs, and other furniture, was the foot pads becoming degraded in some way and falling off. This poses a problem to customers who wish to use the table on anything but carpet. If a footpad falls off it leaves the sharp end of a steel tube to support the table. This can scratch floors causing customer dissatisfaction, not only with the product, but the damage it did to their home.   Given the usage of the table and its construction, user error caused failures were also of concern. These failures involved the table collapsing due to either failure of the user to correctly place the Leg Support Lock Rings or someone leaning on the table in an undesirable way. Upon collapse, the table is one large pinch point that could potentially break small appendages like fingers. The probability of occurrences of these errors are increased by the fact that usage of the table implies imbibing alcohol. The center hinge in the table, while allowing for convenient storage and collapsibility, does decrease the stability of the table. Adding a point of free rotation in the middle of the table surface, what would be a rigid member, adds another mode of possible collapse. If leaned on in the wrong way, the table, with legs still extended, can fold in the middle, at least until the extended legs prevent further motion.

Design for the Environment

Design for the Environment is a system that intends to analyze the entire life cycle of a product to determine the areas of largest impact. In our case the emission of carbon and other greenhouse gases was studied. During the study it was determined that the greenhouse gases produced during use (*) and end of life(*) are negligible compared to those produced during production. It was determined that the production of the table could be split into three parts based on the various components involved: Other plastics product manufacturing for the plastic table top, Iron and Steel Pipe and Tube Manufacturing for the metal table legs, and Screw, nut, and bolt manufacturing for the bolts, screws, and nuts. These three sectors were analyzed for their carbon footprint (Shown below in the graph and chart).

From the study it is apparent that the production of the metal table legs causes the largest carbon footprint. However, it is not too large to warrant trying to find another design solution. For instance, if plastic were used for the legs, a lot of material would have to be used to create the necessary strength, perhaps forfeiting the carbon advantage.

Team Members

Team Leader - Nick Gianopoulos

Use Study - Vlad Kostek

DFMA - Remy Lannelongue

FMEA - Mike Mackin

DFE - Nick Gianopoulos

These assignments were not absolute in the sense that each team member helped on other sections than that which they were assigned. However, each team member was ultimately responsible for completing their assigned part.


Carnegie Mellon University Green Design Institute. (2008) Economic Input-Output Life Cycle Assessment (EIO-LCA), US 1997 Industry Benchmark model [Internet], Available from:[1] Accessed 10 February, 2012.

"Bureau of Economic Analysis." U.S. Department of Commerce. Table 1.1.9. Implicit Price Deflators for Gross Domestic Product, [2] Accessed 11 Feb 2012

"Lowes Lifetime Table" Lowes website, customer review [3] Accessed 13 Feb 2012

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