Materials Used to Make Bulletproof Vests
The current bulletproof vests are made of Kevlar a poly-para-phenylene terephthalamide (Ahmed, Hongpeng, Haijuan, Jing, Yu and Muhuo 2014). This is a liquid polymer that is spun into fiber that is used to make a woven cloth (Ahmed, Hongpeng, Haijuan, Jing, Yu and Muhuo 2014). Kevlar replaced bulky ballistic nylon in making commercial vest after a recommendation by Lester Shubin. Nonetheless, there has emerged a new competitor material for making bulletproof named as Spectra. This is a polyethylene fiber that makes lighter bulletproof vest than those made of Kevlar material.
- Starting with the primary processes and working through to the tertiary processes, illustrate diagrammatically the key stages the product or its components go through.
Manufacturing the Panel Cloth: Kevlar
The first process in the making of a bulletproof vest starts with the preparation of the primary materials. Thus, Kevlar must be produced in the laboratory through polymerization a process that involves combining into a long chain. The resultant material a crystalline liquid is extruded via spinneret metal to form Kevlar threads or yarns. After that, the thread is passed through a cooler to harden the yarn. The threads are then wound into rolls for storage. After manufacturing the Kevlar yarn, the manufacturer sends the role to throwster who twists the fiber into a suitable texture for easy weaving. Lastly, the twisted fiber threads are woven in a pattern either a tabby weave or a just plain weaving (laying the thread in an over and under pattern). When woven into a cloth the piece is ready for sewing into a vest (Tarassuk and Blair 1979).
The process of making a polymer thread
(Source: Ahmed, Hongpeng, Haijuan, Jing, Yu and Muhuo 2014).
Process of making fiber rod by spinneret
(Source: Ahmed, Hongpeng, Haijuan, Jing, Yu and Muhuo 2014)
Rolls of Kevlar ready for sewing into cloth.
The process of making the Spectra is not so different only that the polymer is not woven, but produced in spun of fiber that is placed parallel to one another. The fibers are then coated with the resin sealing them into a cloth sheet. And to make a strong fabric, the sheet of Spectra are put together at a right angle to form a nonwoven cloth fabric that is also sandwiched between two other sheets of polymer material (Bulletproof Vest 2016). Thus, the Spectra material used to sew bulletproof vest is then cut off from the Spectra cloth.
Source: Bulletproof Vest 2016.
Cutting the Cloth Panels. After the Kevlar and Spectra, material is manufactured and rolled together they are sent sold to bulletproof manufacturers that have their primary duty of cutting the panel cloth into sizes and sewing it together into a vest. The material is prepared on top of a table for easy handling because the vest requires more than one layer of either cloth. Expert attests that a layer of eight cloths to twenty-five makes a good bulletproof armor. The manufacturers use a cutting sheet or use computer graphic system to determine the maximal placement of the cut sheet. The idea behind this is to avoid wastage of the expensive material. Once the measurements are complete, a handheld jigsaw machine is used to cut the sheets forming panels that are placed into their precise stacks.
Source: Bulletproof Vest 2016.
Sewing the Cloth Panel Together. Only bulletproof vest made of Kevlar are sewed together by box or quilt stitching. The use of quilt stitching forms diamonds shaped pattern of cloth that is separated by stitches whereas box stitching leaves a single box-shaped pattern in the bulletproof vest as shown in the diagram below. Nonetheless, among the two method quilt stitching is labor intensive, but produces strong panels that make it difficult for users to shift in different direction. On the other hand, box stitching is easy and quick and is comfortable for the user as it moves freely (Bulletproof Vest 2016). Spectra material requires just cutting, and the cloth panel is slanted in layers which are then fit in pouches in the vest.
Source: Bulletproof Vest 2016.
Winding up the Vest. Once the panel is cut into sizes, they are sewn together in a standard determined by the manufacturer using industrial sewing apparatuses. The ready panels are then put inside a vest shell as well as straps are sewn on. As soon as it is complete, the bulletproof vest is packed and sent to the customer.
Source: The U.S. Army
- In no more than 400 words, describe the whole process from beginning to end, explaining more fully exactly what happens at each stage.
The first step in the making of bulletproof vest involves the preparation of ballistic material mostly Kevlar or Spectra. Kevlar just like Spectra is highly strengthened polymers that are spun into a thread of fiber that is used in making of Kevlar cloth materials by intertwining a twisted fiber rod. Once the material is ready, it is sent to the bulletproof manufacturers where it is cut of cloth sewed together to a predetermined multiple layers of the cloth for the material to withstand pressure from ballistic bullets. Once Kevlar cloth is prepared into designed sizes, they are then stuffed in an already readymade vest shell to a complete a full bulletproof vest.
Through the process of making Kevlar and Spectra, bullet differs significantly they produce quality products that protect individual from attack while in the battlefield or as a civilian in their day to day activities. For instance, while Kevlar is produced as a fiber rod that is used to make Kevlar cloth material, Spectra thread are glued together to make a roll of a sheet material. When this is done and transferred to bulletproof makers, the Spectra sheet is used to make spectra cloth by again sticking two sheets together at a right angle and then covering the two with another sheet of cover on both sides. The Spectra panels are then ready to be put in pouches of the prepared vest without sewing or the use of adhesion.
- Examine your selected products materials and processes. Explain under what circumstances its continued production could cease to be sustainable and suggest briefly what could be done
Kevlar and Spectra have served the ballistic industry with exceptional quality because of their strength; verified performances as well as exhibiting a light weight that has ensured bulletproof are light and comfortable. Since 1970s Kevlar and Spectra had won worldwide recognition for improving the performance of ballistic shield materials. Nonetheless, the cost of preparing Kevlar and Spectra has skyrocketed making the materials unattainable shortly. However, scientists have innovated the next generation of a cheaper and advanced fiber known as DuPont and Kevlar Ap (New Kevlar AP for advanced performance 2016). These two products have shown to be more efficient and have an enhanced capability to protect then Spectra and Kevlar. Moreover, the materials are cheap to manufacture with a variety of design that is leaner making the products more robust.
Ahmed, D, Hongpeng, Z, Haijuan, K, Jing, L, Yu, M and Muhuo, Y 2014, Microstructural developments of Poly (p-phenylene terephthalamide) fibers during heat treatment process: a review. Available from: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392014000500012>.
Bulletproof vest, 2016. Available from: < http://www.madehow.com/Volume-1/Bulletproof-Vest.html>.
New Kevlar AP for advanced performance, 2016. Available from: <http://www.dupont.com/products-and-services/fabrics-fibers-nonwovens/fibers/brands/kevlar/products/kevlar-ap.html>.
Tarassuk, L, and Claude, B 1975, The complete encyclopedia of arms and weapons: The most comprehensive reference work every published on arms and armor – with over 1,200 illustrations, Simon and Schuster, New York.