Plywood is made from gluing several sheets of wood (called Veneer) on top of each other, to create a SANDWICH, which is then placed inside a mold and under pressure to dry.

The shape of the mold will form the Sandwich into the intended geometry, and the result will be a single piece of plywood that has been shaped in a 3 dimensional form.

The outside perimeter of the shaped Plywood now needs to be routed, and holes need to be drilled in certain locations of the plywood for later insertion of metal T-Nuts.

Plywood is Stronger than Solid Wood, and can be Bent to form different Shapes. Plywood is used as the Main Structure of Seat, Back, or the Shell of office chairs.

The following 4 elements are crucial parts of making a Quality Part:

• Design
• Machinery & Tooling
• Material
• Manufacturing

9 to 5 Seating has brought in-house many of its manufacturing processes to ensure direct control of the above elements.

Design

Veneer hardness, veneer thickness, number of veneer layers, direction of grain in each layer of veneer, and the positioning of T-Nuts are all important design considerations which affect the structural strength needed in a finished piece of plywood.

9 to 5 Seating designs each plywood part using sophisticated CAD/CAM technologies that ensure the perfect Geometry of each part.  This process is later embedded in the CNC Mold design, Mold fabrication, and the eventual CNC routing of every plywood part manufactured.

Machinery & Tooling

Plywood manufacturing is an ancient technology that has been developed and perfected over the course of history. It involves bonding a number of sheets of veneer together using adhesive. In order for the plywood to form, bend, and take the shape of the mold, the layers of veneer must contain a certain amount of moisture, which together with the moisture present in the adhesive itself, must be dried perfectly well in order for the shaped plywood to maintain its curves and shape once taken out of the mold.

The Machinery & Tooling involved in this process include:

1. Heat Generation System
2. Hydraulic Press, that applies pressure (upward of 100 tons) to press down the mold and the veneer-sandwich inside it
3. Mold, placed in the Hydraulic Presses to form the veneer sandwich
4. Router, to shape the outside perimeter of the  shaped plywood
5. T-Nut insertion drills and presses.

Heat Generation System

There are 2 methods for drying the veneer-sandwich inside a mold:

1. Steam is used to create heat to dry the veneer-sandwich’s moisture. In this system, molds are made with sheets of metal welded together, leaving a hollow space inside the top and bottom halves of the mold. The hollow space inside each half of the mold allows for hot steam to travel in and out, creating heat that will help to dry the moisture within the veneer sandwich.
   
   The advantage of this system is that it is a much cheaper manufacturing process. Basically any waste material is used to burn inside a boiler that generates steam. As a result, this is a preferred method with almost ALL plywood manufacturers in Asia.
   
   The drawback with this method is that the heat is applied to the veneer-sandwich from the Top and the Bottom, trapping moisture within a veneer-sandwich towards its center core. Once de-molded, because it contains trapped moisture in its core, the plywood is likely to twist, warp, and change its shape as the trapped moisture finds its way to come out of the plywood.
   
   
2. High Frequency is used to create Friction, which creates Heat, which is used to Dry the veneer-sandwich’s moisture. In this system, molds are made with solid plywood, with a sheet of aluminum covering the surface of each half of the mold. Each of the two aluminum sheets is connected to the Positive or the Negative poles of a High Frequency Generator, which converts electricity to High Frequency waves. The HF Waves travel from the top half of the mold, through the veneer-sandwich, and all the way to the bottom half of the mold for as long as there is moisture within the veneer-sandwich (since moisture is a conductor of electricity).
   
   The advantage of this system is that HF waves will continue to travel THROUGH the veneer-sandwich until it is 100% dry. Therefore, when the plywood is taken out of the mold it no longer holds any moisture, and as a result the plywood is not likely to ever change its shape, twist, or warp.
   
   The drawback of this system is that electricity is used to create the HF Waves, and electricity is much more expensive than the waste material used under system 1 above.

9 to 5 Seating owns and operates 5 High frequency Generators. The much higher cost of production using High Frequency Generators is well compensated by the quality of product manufactured.

Hydraulic Presses

8 Hydraulic Presses, each with 100 Metric Ton capacity are used in our everyday plywood manufacturing. Our plywood production capacity is sufficient to manufacture more than 4,000 pieces of plywood every single day.

Molds

A unique system, invented and used by 9 to 5 Seating, ensures the symmetry and the perfect geometry of every plywood part manufactured. The system incorporates a drilling mechanism that is designed and built within the mold, drilling perfectly placed Pilot Holes while the mold is still closed during the plywood pressing operation. These perfectly located Pilot Holes are later used for Perfect Positioning of the shaped plywood in our CNC Router during subsequent operations.

CNC Routing

9 to 5 Seating designed, fabricated, and has been using a very sophisticated Routing Machine that is one of a kind in the world. This machine, about 16 feet wide, 14 feet deep, and 7 feet tall, is a totally computer controlled equipment that routes, shapes, and drills every piece of plywood used by 9 to 5 Seating to absolute perfection.

Conventional plywood routing is typically done in one of several ways:

• A very primitive way involves drawing a perimeter line on the plywood and using electric saw to cut and then polish the edges
• A more common way is to use Hand Routers, or Copy Shaping Machines to route the perimeter of the shaped plywood.

The above 2 methods are used commonly in almost all plywood manufacturing factories in China (and most other parts of the Western World). These methods do not have much control over the symmetry of the part that is routed, consequently the end result could be a finished plywood part that leans to one side or other, or is lop sided.

The advantage of the CNC Router is that the Pilot Holes that were drilled during the pressing operation are used to position the part on the CNC Router, mirroring perfectly well the 2 sides of the plywood. Consequently, the finished plywood will be absolutely symmetrical, along with all the holes drilled in precise locations.

Material

Plywood is made using Wood Veneer and Glue.

Wood Veneer:

• Peeled on a lathe from a tree trunk (much like peeling an apple with a knife) in varying thicknesses.
• Hard Wood Trees (such as Eucalyptus Tree) produce Stronger Veneers. Soft Wood Trees (such as Rubber Tree) produce Softer or Weaker Veneers.
• Each sheet of Veneer peeled from a tree will have its Grain going in only ONE DIRECTION. Veneer is hard to bend in the direction of the Grain, and easy to bend in the direction opposite to the Grain.
• If several sheets of Veneer should be laid on top of each other, with the Grain in each sheet facing in the same direction, the result will be a Sandwich that will be very strong in the direction of the Grain, and very weak in the direction opposite to the grain.
• To make a strong Sandwich, each sheet of Veneer in the Sandwich must be laid with the Grain in Alternating Direction from One Veneer to the next Veneer.

Glue

• Glue is a liquid made from mixing a solid sticky substance with liquid, which will turn the solid glue into liquid glue.
• Solid Glue is the strongest Glue, but not practical to apply to a surface.
• Liquid Glue is easy to be applied to a surface, but its strength depends on the percentage of Solid Glue that is in the liquid, and the type of Solid Glue that is used.
• When Glue is applied to two surfaces, the Bonding of the surfaces takes place if the two Glued surfaces are pressed against each other, and kept under pressure until the moisture in the Glue (the liquid) has evaporated and Dried, allowing the Dried Solid Glue to stick the two surfaces together.
• Different Glues have different characteristics, and different Bonding capabilities.

In making Plywood, using strong glue will help make strong plywood. However, the Gluing Process must be done correctly, otherwise the Glue will not bond the surfaces together.

Manufacturing:

Key quality elements to consider in plywood manufacturing include:

• Type of Wood: Hardwood Veneers will make stronger Plywood.
• Veneer Size: Each sheet of veneer must cover the entire size of the Sandwich.
  • A sheet of Veneer that is smaller than the intended surface area, of the Sandwich, will create a weak area in the plywood.
  • Using Veneer scraps, or small pieces of Veneer to cover the surface, will also cause weakness in the structure of Veneer, as well as the possibility of Veneers not Bonding in between the gaps.

• Glue:
  • Good quality Glue, with the Solid portion of the Glue being at about 60% content should be used.
• Pressing:
  • Bonding of veneer sheets directly affects the strength of the plywood.
  • The distance between Mold’s top and bottom surfaces must be perfectly even; otherwise the pressure of the Press will not be evenly distributed over the entire surface of the sandwich, causing some areas of the Sandwich not to bond well together.
  • Pressing and Heating Time must be sufficient to completely dry the Sandwich. If the Press is opened before the Sandwich is completely dry, the veneers will separate from each other and will not Bond.

• Routing:
  • Crooked or Off-Center routing will cause the plywood to lean to one side.