Equipment and Machinery for Paper Making
It is outside the scope of this brief to look in any detail at the enormous variety of equipment and machinery that has been developed for assisting in the paper making process. Broader texts exist which deal more comprehensively with machinery suitable for application to small-scale paper making (see the bibliography at the end of this brief). Many developing countries now manufacture papermaking plant indigenously, making cost savings in manufacture and also in import duties. There are also suppliers in industrialized countries that sell second hand equipment.
Figure 1: Flow of materials through a typical paper making plant (click picture to enlarge)
Figure 1 shows the variety of equipment that is needed for a small hand made paper making process. Much of the machinery required for a mechanized production facility is sophisticated and expensive. Table 2 shows some examples of the equipment that is used for small-scale paper manufacture.
Table 4: Machinery used for small-scale papermaking
Machine Name and Function
- Pulper – An open-topped vessel with impeller which reduces the digested or mechanically reduced stock to a pulp.
- Breaker – Similar in function to the pulper but with blades mounted on a roller inside a bath. Only suitable for batch operation.
- Beater / refiner – Similar to the breaker in appearance but with a beating action for speciality papers. See fig. 2 below.
- Washer – For washing the pulp prior to paper formation.
- Refining equipment – For the final treatment of pulp before being sent to the Fourdrinier machine.
- De-flaking equipment- Used in the preparation of reclaimed paper, these machines are inexpensive and suitable for use in small mills.
- Screen – Situated just prior to the headbox of the paper machine, the screen removes undesirable particles and ensures a uniform suspension of fibers.
- Cleaners – Remove sand or grit from the paper stock by centrifugal action.
- Fourdrinier machine – Used for the formation of the sheet paper. This is the most common type of paper machine
- Headbox or flow-box – The container (similar to a hopper) that feeds the pulp into the paper machine. On smaller machines they usually operate under the pressure of gravity.
- Press – Used to expel water mechanically from the freshly formed paper. Often use hydraulic rams to provide the pressure.
- Dryer – Commonly, a series of steam heated rotating cylinders which help remove the final 50 â€“ 60% of water which still remains after pressing. Solar drying is another option when producing handmade paper.
- Reeling, winding and sheeting equipment – Handling equipment used for final treatment of paper.
- Size press – Machine press for adding starch to the formed sheet paper.
- Cutting machine- Used for the cutting of paper into sheets.
Figure 2: Beater or refiner (click picture to enlarge)
Glossary of Terms
- Cellulose – the material from which all plants, such as trees, wheat stalks, rice-stalks and sugarcane are made.
- Fiber – the long, thread-like wisps from which paper is made.
- Groundwood – pulp obtained by subjecting wood to grindstones in the presence of water, also known as mechanical pulp.
- Flowbox – prepared stock is placed in the flowbox which controls the flow of the pulp through the “slice” onto the “wire”.
- Digestion – cooking of ram fibrous materials to produce pulp.
- Size – liquid added to paper to control ink penetration.
- Bagasse- the fiber remaining when sugar juices has been extracted from sugar cane.
- Furnish – pulp that has been bleached and refined, rinsed and diluted with water, and fillers such as clay or talc may be added.
- Slice – the opening through which pulp flow onto the “wire”. Flow can be under gravity or pressurized.
- Wire – a moving continuous belt of wire or, more commonly nowadays, plastic mesh.