Metal Finishing : Thermal Spraying

Thermal spraying techniques are coating processes in which melted (or heated) materials are sprayed onto a surface. The "feedstock" (coating precursor) is heated by electrical (plasma or arc) or chemical means (combustion flame).

Thermal spraying can provide thick coatings (approx. thickness range is 20 micrometers to several mm, depending on the process and feedstock), over a large area at high deposition rate as compared to other coating processes such as electroplating, physical and chemical vapor deposition. Coating materials available for thermal spraying include metals, alloys, ceramics, plastics and composites. They are fed in powder or wire form, heated to a molten or semimolten state and accelerated towards substrates in the form of micrometer-size particles. Combustion or electrical arc discharge is usually used as the source of energy for thermal spraying. Resulting coatings are made by the accumulation of numerous sprayed particles. The surface may not heat up significantly, allowing the coating of flammable substances.

Coating quality is usually assessed by measuring its porosity, oxide content, macro and microhardness, bond strength and surface roughness. Generally, the coating quality increases with increasing particle velocities.

Metal Finishing : Plating

Plating is a surface covering in which a metal is deposited on a conductive surface. Plating has been done for hundreds of years, but it is also critical for modern technology. Plating is used to decorate objects, for corrosion inhibition, to improve solderability, to harden, to improve wearability, to reduce friction, to improve paint adhesion, to alter conductivity, for radiation shielding, and for other purposes. Jewelry typically uses plating to give a silver or gold finish. Thin-film deposition has plated objects as small as an atom, therefore some plating is nanotechnology.

There are several plating methods, and many variations. In one method, a solid surface is covered with a metal sheet, and then heat and pressure are applied to fuse them (a version of this is Sheffield plate). Other plating techniques include vapor deposition under vacuum and sputter deposition. Recently, plating often refers to using liquids. Metallizing refers to coating metal on non-metallic objects.

Metal Finishing : Heat Treatment

Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. Common heat treatment processes include annealing, precipitation strengthening, quenching, and tempering. The annealing process softens the metal by allowing recovery of cold work and grain growth. Quenching can be used to harden alloy steels, or in precipitation hardenable alloys, to trap dissolved solute atoms in solution. Tempering will cause the dissolved alloying elements to precipitate, or in the case of quenched steels, improve impact strength and ductile properties.

Often, mechanical and thermal treatments are combined in what is known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high alloy special steels, super alloys and titanium alloys.

Some Type Of Material

Little is known about this process, what type of machinery it uses or how it benefits our lives. The truth is simple. The process of metal stamping and the products it produces are virtually unlimited. Today, this process helps your car operate, medical equipment function and supplements other key components of our daily life.

Metal stamping operations utilize leading precision stamping presses including Bruderer, Kyori, Ingyu, and Minster with sizes ranging from 5 tons - 220 tons. Materials used in the process include Beryllium Copper, Phosphorous Bronze, Stainless Steel & Copper and Cold Rolled Steel with thickness ranging from 0.002" to 0.180". As a result, manufacturers have the capability to provide services and products for a wide variety of industries.

The Metal Stamping Process is put to use for a number if industries, including:

* Automotive parts stamping
* Medical stamping
* Stamping for mobile devices
* Stamped and drawn shields for industrial and electronics industries
* Bandolier
* Bandolier wire
* Header pins
* Contact pins
* Terminals
* Sleeved terminals
* Reel to reel
* Precision miniature stamping
* High speed
* Micro
* Stainless steel
* Medical Stamping

In addition, several types of metals are used in the process, including:

* Aluminum
* Beryllium
* Brass
* Bronze
* Cold Rolled Steel
* Copper
* Mylar
* Phenolic
* Stainless Steel
* Teflon
* Titanium and more!

The parts manufactured during the stamping process vary from tiny parts in material as thin as .05mm to larger frames and heavy duty metal components. Precision presses vary in size from 5 tons to 220 tons, and with speeds up to 1,500 per minute. Stamping services also have skiving equipment to contour metal thickness and configuration as required.

The Important Function of Metal Stamping Dies

Metal stamping dies are the devices used in metal stamping machines. Each metal stamping machine can have one or more than one dies depending on the kind of machine. Dies are the main components in metal stamping machines that do the actual casting, punching, cutting and shaping of the metal sheet.

The basic die operations are drawing, shearing and bending. In metal stamping, the metal sheets are placed in a die or a press tool which has a specially designed cavity that gives the preferred shape to the metal sheet. The upper part of the die connects to the press slide while the lower component connects to the press bed. A specific component known as the punch pushes the metal sheet through the die, thus performing the actual shaping operation. The patterns on the dies can be used to emboss or give three-dimensional lettering on the final product.

Dies are placed in sheet metal panels either alone or as a series of presses in a press line. Metal stamping dies and presses can have different input variables on the bases of tonnage, press parallelism, shut height, nitrogen pressure in dies, counterbalance pressure and press speed. These variables can influence the quality of the stamping panel, particularly during die setup. The same stamping press can be reused by replacing one set of dies with another.

The placement of dies in a press is known as die setup. Die setup decides the shut height and binder force. The number of components produced in a die setup is known as a batch.

There are many different kinds of dies such as single station dies, multiple station dies, compound dies, progressive dies and tandem press lines. Most dies are designed by the metal stamping companies who use advanced technologies like CAD to design them according to customer specifications. Another classification of dies is draw dies, trim dies and cam-pierce dies.

Process control

Process control is a statistics and engineering discipline that deals with architectures, mechanisms, and algorithms for controlling the output of a specific process. See also control theory.

For example, heating up the temperature in a room is a process that has the specific, desired outcome to reach and maintain a defined temperature (e.g. 20°C), kept constant over time. Here, the temperature is the controlled variable. At the same time, it is the input variable since it is measured by a thermometer and used to decide whether to heat or not to heat. The desired temperature (20°C) is the setpoint. The state of the heater (e.g. the setting of the valve allowing hot water to flow through it) is called the manipulated variable since it is subject to control actions.

A commonly used control device called a programmable logic controller, or a PLC, is used to read a set of digital and analog inputs, apply a set of logic statements, and generate a set of analog and digital outputs. Using the example in the previous paragraph, the room temperature would be an input to the PLC. The logical statements would compare the setpoint to the input temperature and determine whether more or less heating was necessary to keep the temperature constant. A PLC output would then either open or close the hot water valve, an incremental amount, depending on whether more or less hot water was needed. Larger more complex systems can be controlled by a Distributed Control System (DCS) or SCADA system.

In practice, process control systems can be characterized as one or more of the following forms:

    * Discrete – Found in many manufacturing, motion and packaging applications. Robotic assembly, such as that found in automotive production, can be characterized as discrete process control. Most discrete manufacturing involves the production of discrete pieces of product, such as metal stamping.

    * Batch – Some applications require that specific quantities of raw materials be combined in specific ways for particular durations to produce an intermediate or end result. One example is the production of adhesives and glues, which normally require the mixing of raw materials in a heated vessel for a period of time to form a quantity of end product. Other important examples are the production of food, beverages and medicine. Batch processes are generally used to produce a relatively low to intermediate quantity of product per year (a few pounds to millions of pounds).

    * Continuous – Often, a physical system is represented through variables that are smooth and uninterrupted in time. The control of the water temperature in a heating jacket, for example, is an example of continuous process control. Some important continuous processes are the production of fuels, chemicals and plastics. Continuous processes in manufacturing are used to produce very large quantities of product per year (millions to billions of pounds).

Piercing Process

What Is Piercing
Piercing is a shearing process where a punch and die are used to create a hole in sheet metal or a plate. The process and machinery are usually the same as that used in blanking, except that the piece being punched out is scrap in the piercing process. There are many specialized types of piercing: lancing, perforating, notching, nibbling, shaving, cutoff, and dinking.

The amount of clearance between a punch and die for piercing is governed by the thickness and strength of the work-piece material being pierced. The punch-die clearance determines the load or pressure experienced at the cutting edge of the tool, commonly known as point pressure. Excessive point pressure can lead to accelerated wear and ultimately failure.

Burr height is typically used as an index to measure tool wear, because it is easy to measure during production.

Specialized types

Lancing
Lancing is the manufacturing process where a piece of material is sheared and bent in order to make tabs, vents, and louvers. A key part of this process is that there is not reduction of material, only a modification in its geometry.

There are three key characteristics to the process of lancing:
1. The material is only modified, nothing is removed.
2. One or more cuts are made, with the remainder being bent to the necessary angle or curve.
3. Ability to make a special feature in a part using only one cut in the material.

The cut made in lancing is not a closed cut, like in perforation even though a similar machine is used, but a side is left connected to be bent sharply or in more of a rounded manner. Mechanical presses are used to perform lancing, commonly

Lancing can be used to make partial contours and free up material for other operations further down the production line. Along with these reasons lancing is also used to make tabs (where the material is bent at a 90 degree angle to the material), vents (where the bend is around 45 degrees), and louvers (where the piece is rounded or cupped).

Normally lancing is done on a mechanical press, lancing requires the use of punches and dies to be used. The different punches and dies determine the shape and angle (or curvature) of the newly made section of the material. The dies and punches are needed to be made of tool steel to withstand the repetitious nature of the procedure.

Perforating
The perforating process involves piercing a large number of closely spaced holes

Notching
The notching process removes material from the edge of the workpiece.

Nibbling
The nibbling process cuts a contour by producing a series of overlapping slits or notches. This allows for complex shapes to be formed in sheet metal up to 6 mm (0.25 in) thick using simple tools. The nibbler is essentially a small punch and die that reciprocates quickly; around 300–900 times per minute. Punches are available in various shape and sizes; oblong and rectangular punches are common because they minimize waste and allow for greater distances between strokes, as compared to a round punch. Nibbling can occur on the exterior or interior of the material, however interior cuts require a hole to insert the tool.

The process is often used on parts that do not have quantities that can justify a dedicated blanking die. The edge smoothness is determined by the shape of the cutting die and the amount the cuts overlap; naturally the more the cuts overlap the cleaner the edge. For added accuracy and smoothness most shapes created by nibbling undergo filing or grinding processes after completion.

Shaving
The shaving process is a finish operation where a small amount of metal is sheared away from an already blanked part. Its main purpose is to obtain better dimensional accuracy, but secondary purposes include squaring the edge and smoothing the edge. Blanked parts can be shaved to an accuracy of up to 0.025 mm (0.001 in).

Cutoff
The cutoff process is used to separate a stamping or other product from a strip or stock. This operation is very common with progressive die sequences. The cutoff operation often produces the periphery counter to the workpiece