The blow molding process begins with melting down the plastic and forming it into a parison or in the case of injection and injection stretch blow moulding a preform. The parison is a tube-like piece of plastic with a hole in one end through which compressed air can pass.
The parison is then clamped into a mold and air is blown into it. The air pressure then pushes the plastic out to match the mold. Once the plastic has cooled and hardened the mold opens up and the part is ejected.
2. What is cement or Board Lasting?
A lasting process where the insole board (cardboard or Texon board) is inserted onto the last bottom and the lasting margin (excess) material of the upper is lasted/pulled) onto the board and cemented to the insole board. Shoes of this type are usually stiffer and heavier. A special machine is used pull the upper and cement in place.
3. Compression set or Compression resistance?
For foam products in shoe manufacture we like to know how long foam will last if we build it into a footbed or shoe midsole. Simply put the compression set is how much a foam will bounce back after being compressed. Compression set is measured in a Percentage. A foam that resists compression could have a score of 4%, a foam that is badly damaged by impact may have a score of 45%.
Poor quality EVA will have a high compression set value. High quality PU foam will last forever with a very low compression set.
Cutting loss is the material left over once the shoe parts are cut from a material. Depending on the material type the cutting loss can be between 2% to 15%. The cutting loss also depends on the size and shape of the parts being cut. Mech will have a low cutting loss, leather may be higher. It's important to keep the cutting loss to a minimum as this loss will be added to the cost of the shoe. A skilled cutter will save the factory money!
5. Explain designers or Shoe Designers?
Someone has to draw the shoes. Depending on who you ask, this is the easiest part or the hardest. The designer has to draw what people want on their feet. Hmm..
To be a shoe designer, art school would be a great help. A degree in Industrial or Product design is a great place to start. But that said, if you can really draw like a bandit who needs higher education? The designers draw the shoes, then work with the developers to make the prototypes just right. Picking color trends and knowing what is cool are critical skills.
6. What is EVA or CM EVA foam?
Compression Molded EVA or Ethylene vinyl acetate. A foamed midsole material that offers good cushioning and compression set. Nike likes to call theirs “Phylon” but it is the same stuff whatever you call it. The most common foam for shoe midsoles. easy for for by cutting, molding, injecting. It's light and durable. EVA can be made in many grades depending on the compound. More or less filler, more or less vinyl acetate in the mix. can be made pillow soft or rock hard.
7. What is full Grain leather?
Full-grain leather refers to hides that have not been sanded, buffed, or snuffed (as opposed to top-grain or corrected leather) to remove imperfections (or natural marks) on the surface of the hide. The grain remains allowing the fiber strength and durability. The grain also has breathability, resulting in less moisture from prolonged contact. Rather than wearing out, it will develop a patina over time. High quality leather furniture and footwear are often made from full-grain leather.
The heel lift of a shoe or shoe last is the dimension specified for the heel height above the ground. This is determined by the last if a shoe. A normal sport shoe will generally have a heel lift of 6 to 8mm above the ball of the foot. This is a standard ergonomic stance that will allow the shoe to have more cushioning under the heel. A causal shoe or sandal may have a lift of zero, then of course a high heel women's shoe last can have a heel lift of 4 inches or more!
Lasting is the operation that stretches the shoe upper over the foot form or last. Almost all shoe are lasted in some way. With the last inside the upper the outsole can be bonded and pressed into place. Once the outsole is bonded the shoe can be De-lasted. There are several types of lasting operations. Slip lasting, board lasting, toe lasting, waist lasting, heel lasting, string lasting, California lasting and hand lasting.
10. What is MTO or Made to Order or Make to Order?
Made to order or MTO is a special production run of shoes. The MTO shoes can be for a specific shoe store or international distributor. Usually a special color or material treatment. The MTO product manager will work closely with sales managers, Product line managers, sales reps and Designers to create new products. MTO projects can be brought to market quickly as there is no selling or booking period required. Once the design is confirmed the order can be placed to the factory.
11. What is outsole Channel stitch?
The shoe outsole will have a small groove or two molded into the rubber sidewall. After the shoe is assembled a heavy duty stitching machine with a special bent arm is used to stitch a heavy thread through the rubber sole and the upper of the shoe. This channel stitch is often used on the toe tip of joggers, the side wall of skate shoe and the bottoms of boat shoes.
12. What are product Managers or Product Line Managers?
The Product Manager or “PM” is the person that sets designer and developer in motion. It's the PM's job to figure out what to make. The PM will tell the designer what kind of shoe to make. PM's responsibility is to work with the sales team and customers to find out what they need. The PM is also tasked with looking forward. What will people need next year? What color shoes will be trending? Experience in retail or sales is a big help. Designer and developers are often promoted to this position. A marketing degree will help.
Minimum order quantity Shoe factories and material makers ofter have an MOQ. Based on dye lot size or machine operation. For example, a special mesh may require machine set up so the MOQ may be 500 meters. To dye a stock material may make the MOQ 50 meters.
14. What is letter of Credit LC term of payment?
A letter of credit is a promise between businesses to pay. The buyers and sellers contract banks issue letters of credit as a way to ensure that sellers get paid as long as they do what they've agreed to do. The LC is common in international trade even though its more expensive to transact than a T/T, as it guarantees that a payment will be made if certain conditions are met.
ISNR 20 (TSAR 20) is general purpose rubber graded by precise technical standards and not by visual characteristics. Some standards may vary marginally based on the origin. Technically Specified Rubber (TSAR) is used for making tires, tubes, rubber mats, cushion gum stock, raincoat proofings, micro-cellular sheet for upholstery and packing, conveyor belts, footwear and various other rubber products.
16. What is grading or Size Grade?
Making different shoe sizes. The sample size or development size is usually Men's 9 and Women's 7. Once the sample is confirmed, extreme sizes are made size 5 and size 12. Then all the sizes are graded. The word is a noun and a verb. Can I see the size grade? or, the pattern master is grading the pattern. The pattern grade is now done by computer then checked by the pattern master.
17. What is FOB Free On Board Purchase Term?
When you negotiate a shoe price you need be clear on where the finished shoe is to be delivered. In most cases the shoe price will be stated as FOB (the nearest freight harbor). In south China it would be FOB Yantian. So the seller is responsible for the inland trucking the goods to the the freight terminal. (see Ex-Works Price)
18. Explain developers or Shoe Developers?
Not a shoe designer but critical to getting the shoes made. It's the footwear developers job is to take a nice drawing and make it into a real shoe you can wear on your feet. The shoe developer is the guy that writes the technical specifications, checks the blue prints, and communicates with the shoe factory.
The shoe developers job is to get the shoe made and keep the free thinking designers from making a beautiful shoe that is cruel to wear. Footwear developers are the shoe prototype engineers and schedule keepers. To be a shoe developer you may start as a designer, an intern or assistant. Be ready to travel!
The most popular shoe-tying is a simple crisscross, each end of the shoelace pulled through the next eyelet on the opposite flap.
fastener consisting of a metal ring for lining a small hole to permit the attachment of cords or lines
20. Explain shoe parts Cutting Dies?
Used to cut out shoe parts. These steel cutting dies look just like cookie cutters. Each die is coated with rust proof paint and marked with the shoe size and model number. Making a shoe requires hundreds of dies. One die for each part, for every size of a shoe.
21. What is corrected-grain leather?
Corrected-grain leather is any leather that has had an artificial grain applied to its surface. The hides used to create corrected leather do not meet the standards for use in creating vegetal-tanned or aniline leather. The imperfections are corrected or sanded off, and an artificial grain embossed into the surface and dressed with stain or dyes. Most corrected-grain leather is used to make pigmented leather as the solid pigment helps hide the corrections or imperfections. Corrected grain leathers can mainly be bought as two finish types semi-aniline and pigmented.
22. What is cold Cement shoe making process?
Bonding process to attach the upper to the outsole that does not require the upper to be placed into an oven. The outsole unit made of rubber and EVA foam is completely cured. PU cement, Water massed of solvent based is used to attached the sole unit to the lasted upper. Cold cementing does require heating tunnels to dry the surface primer and cement. Typically the upper and outsole receive one layer of surface primer and two layers of shoe cement before they are fit together. Once the parts are fit together a hydraulic ram is used to press the parts, typically 3 operations from the top, sides them front to back.
23. What is shoe cement Bonding Margin?
The amount of space required to have a cement bond. If the rubber has only a 2mm bonding margin the outsole may peel off the outsole. A 12mm bonding margin would be better.
Suede cow leather that is covered with a thin coating of Polyurethane. The coating can be any color and can be embossed with a roller. The final product is generally a solid color leather looking product. This material is still classified as leather for import duty. Almost all white sneakers are made with action leather.
Microfiber Synthetic Leather. These high quality micro fiber suede materials can be expensive but they are great for use on shoes, gloves, linings and trim.
