Tuesday, November 3, 2009

Parts of a Vernier Caliper

A Caliper is simply a measuring device from a compass to intense instruments such as the vernier caliper acting as an advanced ruler. The vernier caliper uses vernier scale to measure more precisely. This instrument provides different methods of measuring including ways to measure external or internal dimensions as well as finding depth measurements. In fact the depth measurement method of using a movable and slidable probe is so slender that it is able to retrieve data in deep canals.

You have to be familiar with the instrument in order for your to achieve an accurate measurement. Any discrepancy from of measurement even for just a few millimeters will spell success of trouble for you. Machinist are experts on this device. But evenso, they still need to exercise caution.

The lower and upper section of this scale generally uses both inch and metric measurements. Industries use vernier calipers because of its hundredth of a millimeter precision equal to one thousandth of an inch. Below describes the vernier caliper's parts and functions.

Vernier Caliper
The rail (4) allows sliding to occur on the main scale (7) moving the vernier scale (3) while the fixed jaw (11) remains in place so the precise measurement is found. Also, draw back and forth (9) the instrument's jaws (parts 1 and 10) to adjust the caliper. The indicated measurement is found at the left of the vernier scale (3 and 8) either in inches or centimeters. The sliding jaw (9) and the depth probe (5) are connected to and move along with the vernier scale. Deep measurements are taken by the use of the front end of the rail (6).
  1. Inside jaws: Internal length measurements are found by using this part.
  2. Retainer or locking screw: This part blocks the instrument's movable parts in order to transfer between measurement methods easily.
  3. Vernier scale (inch)
  4. Rail (inch)
  5. Depth probe: The part used in order to find depth measurements
  6. Front end of the rail
  7. Main scale (mm)
  8. Vernier scale (mm)
  9. Sliding Jaw
  10. Outside jaws: This part makes measuring external lengths possible.
  11. Fixed Jaw


Saturday, October 31, 2009

The Vernier Caliper

The Caliper. The name itself is generic. But to define it, it is a device used to measure the distance between to symmetrically opposing sides. A caliper can be as simple as a compass with inward or outward-facing points. The tips of the caliper are adjusted to fit across the points to be measured, the caliper is then removed and the distance read by measuring between the tips with a measuring tool, such as a ruler.

They are used in many fields such as metalworking, mechanical engineering, gunsmithing, handloading, woodworking, woodturning and in medicine.

There are many types of Calipers but obviously in relation to this blog, we'll mention a particular type of caliper namely: The Vernier Caliper.

Vernier Calipers are usually found in machine shops or any other area which requires to measure its fabricated dimensions. Without this device, machine shops will be having a hard time for accurate measurement.

Vernier calipers can measure internal dimensions (using the uppermost jaws in the picture at right), external dimensions using the pictured lower jaws, and depending on the manufacturer, depth measurements by the use of a probe that is attached to the movable head and slides along the centre of the body. This probe is slender and can get into deep grooves that may prove difficult for other measuring tools.

The vernier scales may include both metric and inch measurements on the upper and lower part of the scale.

Vernier calipers commonly used in industry provide a precision to a hundredth of a millimetre (10 micrometres), or one thousandth of an inch.

A more precise instrument used for the same purpose is the micrometer.


Sunday, October 25, 2009

Metals Knowledge: Machining Nonferrous Metals

Some of the alloys of aluminum have been machined successfully without any lubricant or cutting compound, but in order to obtain the best results, some form of lubricant is desirable. Tools for aluminum and aluminum alloys should have larger relief and rake angles than tools for cutting steel.

Magnesium alloys are readily machined and with relatively low power consumption per cubic inch of metal removed. The usual practice is to employ high cutting speeds with relatively coarse feeds and deep cuts. Exceptionally fine finishes can be obtained so that grinding to improve the finish usually is unnecessary.

Machining of zinc alloy die-castings is mostly done without a lubricant. For particular work, a lubricant may be used to advantage.

Machining Aluminum

Some of the alloys of aluminum have been machined successfully without any lubricant or cutting compound, but in order to obtain the best results, some form of lubricant is desirable. For many purposes, soluble cutting oil is good.

Tools for aluminum and aluminum alloys should have larger relief and rake angles than tools for cutting steel. For high-speed steel turning tools the following angles are recommended: relief angles, 14 to 16 degrees; back rake angle, 5 to 20 degrees; side rake angle, 15 to 35 degrees. For very soft alloys even larger side rake angles are sometimes used.

High silicon aluminum alloys and some others have a very abrasive effect on the cutting tool. While these alloys can be cut successfully with high-speed steel tools, cemented carbides are recommended because of their superior abrasion resistance. The tool angles recommended for cemented carbide turning tools are: relief angles, 12 to 14 degrees; back rake angle, 0 to 15 degrees; side rake angle, 8 to 30 degrees.

Cut-off tools and necking tools for machining aluminum and its alloys should have from 12 to 20 degrees back rake angle and the end relief angle should be from 8 to 12 degrees. Excellent threads can be cut with single-point tools in even the softest aluminum.

Experience seems to vary somewhat regarding the rake angle for single-point thread cutting tools. Some prefer to use a rather large back and side rake angle although this requires a modification in the included angle of the tool to produce the correct thread contour. When both rake angles are zero, the included angle of the tool is ground equal to the included angle of the thread. Excellent threads have been cut in aluminum with zero rake angle thread-cutting tools using large relief angles, which are 16 to 18 degrees opposite the front side of the thread and 12 to 14 degree: opposite the back side of the thread. In either case, the cutting edges should be ground and honed to a keen edge. It is sometimes advisable to give the face of the tool a few strokes with a hone between cuts when chasing the thread in order to remove any built-up edge on the cutting edge.

Fine surface finishes are often difficult to obtain on aluminum and aluminum alloys, particularly the softer metals. When a fine finish is required, the cutting tool should be honed to a keen edge and the surfaces of the face and the flank will also benefit by being honed smooth. Tool wear is inevitable; however, it should not be allowed to progress too far before the tool is changed or sharpened.

A sulphurized mineral oil or heavy-duty soluble oil will sometimes be helpful in obtaining a satisfactory surface finish. For best results, however, a diamond cutting tool is recommended. Excellent surface finishes can be obtained on even the softest aluminum and aluminum alloys with these tools.

Although ordinary milling cutters can be used successfully in shops where aluminum parts are only machined occasionally, the best results are obtained with coarse tooth, large helix-angle cutters having large rake and clearance angles. Clearance angles up to 10 to 12 degrees are recommended. When slab milling and end milling a profile, using the peripheral teeth on the end mill, climb milling will generally produce a better finish on the machined surface than conventional milling. Face milling cutters should have a large axial rake angle.

Standard twist drills can be used without difficulty in drilling aluminum and aluminum alloys although high helix-angle drills are preferred. The wide flutes and high helix-angle in these drills helps to clear the chips. In some cases the use of split-point drills is preferred. Carbide tipped twist drills can be used for drilling aluminum and its alloys which may afford advantages in some production applications.

Ordinary hand and machine taps can be used to tap aluminum and its alloys although spiral-fluted thread taps give superior results.

Machining Magnesium

Magnesium alloys are readily machined and with relatively low power consumption per cubic inch of metal removed. The usual practice is to employ high cutting speeds with relatively coarse feeds and deep cuts. Exceptionally fine finishes can be obtained so that grinding to improve the finish usually is unnecessary.

The horsepower normally required in machining magnesium varies from 0.15 to 0.30 per cubic inch per minute. While this value is low, especially in comparison with power required for cast iron and steel, the total amount of power for machining magnesium usually is high because of the exceptionally rapid rate at which metal is removed.

Carbide tools are recommended for maximum efficiency, although high-speed steel frequently is employed. Tools should be designed so as to dispose of chips readily or without excessive friction, by employing polished chip-bearing surfaces, ample chip spaces, large clearances, and small contact areas.

Feeds and Speeds for Magnesium: Speeds ordinarily range up to 5000 feet per minute for rough- and finish-turning, up to 3000 feet per minute for rough-milling, and up to 9000 feet per minute for finish-milling.

Lathe Tool Angles for Magnesium: The true or actual rake angle resulting from back and side rakes usually varies from 10 to 15 degrees. Back rake varies from 10 to 20, and side rake from 0 to 10 degrees. Reduced back rake may be employed to obtain better chip breakage. The back rake may also be reduced to from 2 to 8 degrees on form tools or other broad tools to prevent chatter.

Parting Tools: For parting tools, the back rake varies from 15 to 20 degrees, the front end relief 8 to 10 degrees, the side relief measured perpendicular to the top face 8 degrees, and the side relief measured in the plane of the top face from 3 to 5 degrees.

Milling Magnesium. In general, the coarse-tooth type of cutter is recommended. The number of teeth or cutting blades may be one-third to one-half the number normally used; however, the two-blade fly-cutter has proved to be very satisfactory. As a rule, the land relief or primary peripheral clearance is 10 degrees followed by secondary clearance of 20 degrees.

Drilling Magnesium. If the depth of a hole is less than five times the drill diameter, an ordinary twist drill with highly polished flutes may be used. The drill should be kept sharp and the outer corners rounded to produce a smooth finish and prevent burr formation. For deep hole drilling, use a drill having a helix angle of 40 to 45 degrees with large polished flutes of uniform cross-section throughout the drill length to facilitate the flow of chips. Drilling speeds vary from 300 to 2000 feet per minute with feeds per revolution ranging from 0.015 to 0.050 inch.

Tapping Magnesium. Standard taps may be used unless Class 3B tolerances are required, in which case the tap should be designed for use in magnesium. A high-speed steel concentric type with a ground thread is recommended. The concentric form, which eliminates the radial thread relief, prevents jamming of chips while the tap is being backed out of the hole. The positive rake angle at the front may vary from 10 to 25 degrees and the "heel rake angle" at the back of the tooth from 3 to 5 degrees. The chamfer extends over two to three threads. For holes up to 1/4 inch in diameter, two-fluted taps are recommended; for sizes from 1/2 to 3/4 inch, three flutes; and for larger holes, four flutes. Tapping speeds ordinarily range from 75 to 200 feet per minute, and mineral oil cutting fluid should be used.

Threading Dies for Magnesium. Threading dies for use on magnesium should have about the same cutting angles as taps. Narrow lands should be used to provide ample chip space. Either solid or self-opening dies may be used. The latter type is recommended when maximum smoothness is required. Threads may be cut at speeds up to 1000 feet per minute.

Grinding Magnesium. As a general rule, magnesium is ground dry. The highly inflammable dust should be formed into sludge by means of a spray of water or low viscosity mineral oil. Accumulations of dust or sludge should be avoided. For surface grinding, when a fine finish is desirable, a low-viscosity mineral oil may be used.

Machining Zinc Alloy Die-Castings

Machining of zinc alloy die-castings is mostly done without a lubricant. For particular work, especially deep drilling and tapping, a lubricant such as lard oil and kerosene or a 50-50 mixture of kerosene and machine oil may be used to advantage. A mixture of turpentine and kerosene has been found effective on certain difficult jobs.

Reaming: In reaming, tools with six straight flutes are commonly used, although tools with eight flutes irregularly spaced have been found to yield better results by one manufacturer. Many standard reamers have a land that is too wide for best results. A land about 0.015 inch wide is recommended but this may often be ground down to around 0.007 or even 0.005 inch to obtain freer cutting, less tendency to loading, and reduced heating.

Turning: Tools of high-speed steel are commonly employed although the application of Stellite and carbide tools, even on short runs, is feasible. For steel or Stellite, a positive top rake of from 0 to 20 degrees and an end clearance of about 15 degrees is commonly recommended. For boring, facing, and other lathe operations, rake and clearance angles are about the same as for tools used in turning.

Machining Monel and Nickel Alloys

These alloys are machined with high-speed steel and with cemented carbide cutting tools. High-speed steel lathe tools usually have a back rake of 6 to 8 degrees, a side rake of 10 to 15 degrees, and relief angles of 8 to 12 degrees. Broad-nose finishing tools have a back rake of 20 to 25 degrees and an end relief angle of 12 to 15 degrees. In most instances, standard commercial cemented-carbide tool holders and tool shanks can be used which provide acceptable tool geometry. Honing the cutting edge lightly will help if chipping is encountered.

The most satisfactory tool materials for machining Monel and the softer nickel alloys, such as Nickel 200 and Nickel 230, are M2 and T5 for high-speed steel and crater resistant grades of cemented carbides. For the harder nickel alloys such as K Monel, Permanickel, Duranickel, and Nitinol alloys, the recommended tool materials are T15, M41, M42, M43, and for high-speed steel, M42. For carbides, a grade of crater resistant carbide is recommended when the hardness is less than 300 Bhn, and when the hardness is more than 300 Bhn, a grade of straight tungsten carbide will often work best, although some crater resistant grades will also work well.

A sulfurized oil or a water-soluble oil is recommended for rough and finish turning. A sulfurized oil is also recommended for milling, threading, tapping, reaming, and broaching.

Nickel alloys have a high tendency to work harden. To minimize work hardening caused by machining, the cutting tools should be provided with adequate relief angles and positive rake angles. Furthermore, the cutting edges should be kept sharp and replaced when dull to prevent burnishing of the work surface. The depth of cut and feed should be sufficiently large to ensure that the tool penetrates the work without rubbing.


XYZ takes orders: expands services

A recent series of Open Days hosted at XYZ Machine Tools Ltd's regional showrooms resulted in orders valued at nearly £700,000, while details of expanded services were announced.

XYZ takes orders expands servicesThe show, held in Blackburn, Nuneaton and Waltham Abbey, saw orders for CNC/manual mills and lathes and full-CNC machine tools, and this, said managing director Nigel Atherton, provided the backdrop to what he sees as a more positive attitude to capital investment from manufacturing industry.

"There are clear signs of an improvement in business confidence," he said, "although it is still too early to be sure that this is more than a blip and that the worst of the recession is behind us. However, we had visitors representing more than 60 companies, and the interest shown, the orders placed and the enquiries in progress are very encouraging."

Price, of course, is a key factor in any capital equipment purchase but, said the managing director: "We believe it is vitally important to help our customers lower the overall cost of machine tool ownership. One way of achieving this is by providing high quality service and support, together with better and more efficient training. This is why we are expanding XYZ's training and applications team, with these latest open days coinciding with an extension of the team's customer service remit."

Customers already receive basic training free-of-charge when purchasing an XYZ machining centre, turning centre or large CNC lathe equipped with Siemens CNC, or any CNC/manual turret/bed mill or lathe equipped with the exclusive ProtoTRAK control. The Burlescombe, Devon-based company also organises refresher and advanced training days designed to help users of its machine tools to obtain the maximum benefit from their investments. Now it is extending the help available to customers buying its Siemens-equipped full-CNC machine tools with the offer of up to eight days free-of-charge applications assistance worth up to £4,800.

"This is additional to the three days' free-of-charge basic training already provided with our full-CNC range of machines," Mr Atherton underlined. "Our objective is to speed up the learning process and to help customers avoid the frustrations that can occur following installation and commissioning of a CNC machine. The first few days are when even the most experienced operator taking on a new control can produce expensive scrap, bad habits can take hold and valuable time can be wasted. However, with expert applications assistance on hand in your machine shop, this need never happen."


Saturday, October 24, 2009

Mills CNC claims big market share for big machines

Mills CNC claims over 50 per cent of the UK's large lathe market (chuck size 12" and over), 50 per cent of the large VTL (Vertical Turning Lathe) market and significant market share in the large horizontal machining centre and horizontal borer markets.

Mills CNC claims big market share for big machinesThe company is the exclusive UK and Ireland distributor for Doosan machine tools, and highlights that the portfolio has recently been broadened with the launch of a new range of 5-face, double-column machining centres, DCM, within which there are eight different sized.

The new DCM machines, with up to 10, 250 by 4,200 by 700, by 1,100 mm in X, Y, Z and W, can parts up to 68,000 kg in weight.

Depending on the type of application, DCM machines can be specified with various ram spindle configurations (heavy-duty cutting through to high-speed/high-torque options); different head attachments and table types.

"The Doosan big machine tool range is impressive – and the new DCM machines are no exception," underlines Nick Frampton, Mills CNC's managing director.

"In terms of breadth, depth, technical specification, and all-round performance and price – big Doosan machines are the number one choice for precision manufacturers in the oil and gas, power generation and other sectors where the machining of large components is at a premium."


Saturday, October 17, 2009

Lathe Tools offer maximum speed of 12,000 rpm.

SMW Autoblok is pleased to introduce spindle speed increasing Live Tools for Haas lathes. These new low-profile Live Tools feature a 1:3 speed increasing ratio and a maximum speed of 12,000RPM.

Designed to increase the performance of Haas lathes with 4,000RPM driven turrets, SMW Autoblok's new spindle speed increasing Live Tools can drastically reduce cycle times and duty cycles, particularly in finishing application in mild steels, aluminum, plastics, and reinforced resins. With an ultra-low profile of 88.5mm (3.48"), these new Live Tools are no taller than a standard Live Tool, preserving Z-axis clearance for work-holding and parts. Additionally, with their minimal width of 80mm (3.15"), they do not interfere with adjacent tools in the turret.

SMW Autoblok's new spindle speed increasing Live Tools utilize patented square drive Gleason matched ground helical gears for improved torque transmission and high quality twin interlocking labyrinth seals to prevent contamination from coolant and chips. The new compact ER clamping design makes for easy tool changes, higher clamping forces, extended drill lengths, and improved rigidity.

SMW Autoblok also offers standard Live Tools for Haas lathes in straight, right angle, and offset styles equipped with either an ER Collet or Face Mill output spindle. Coolant-thru the tool up to 1,000PSI is available on most styles, and special application Live Tools are available upon request. SMW Autoblok stocks Live Tools for other popular CNC Turning Centers including Mazak, Mori Seiki, Okuma, and Doosan and more.

For more information on Live Tools or other SMW Autoblok products, please contact SMW Autoblok Corporation at 847-215-0591 or visit www.live-tooling.com.

ABOUT SMW AUTOBLOK CORPORATION - Autoblok Corporation was established in 1981 as a subsidiary of Autoblok of Italy, the largest power chuck manufacturer in Europe. Since 1942, Autoblok has been at the forefront of engineering and manufacturing state-of-the-art workholding, clamping and tooling solutions. In 1993, Autoblok acquired SMW of Germany. The combination of these two premier manufacturing entities resulted in the most extensive product line of high quality workholding devices in the world. Now available exclusively through its subsidiaries, reps and distributors, SMW AUTOBLOK customers are ensured a consistent, single source of superior product performance, support and service.


K+K moves to expand machining business

Bletchley-based subcontractor K+K Specialised Engineering has moved to new premises to accommodate extra XYZ CNC machine tools and allow for future growth.

Prototype electronics box milled from solid aluminium block by K+K Specialised Engineering
Prototype electronics box milled from solid aluminium block by K+K Specialised Engineering

The company currently machines precision components for the automotive development, motorsport, microwave communications and mechanical handling industries, as well as making jigs and fixtures for UK-based metrology companies.

Commenting on the move K+K director Keith Pain explains: “We would not have done this if it did not make sound economic sense. Our problem, if you can call it that, was that we had become the favoured supplier to several businesses that had also flourished by being responsive to their customers. We were regularly being asked to produce small batches of components instead of just one-offs in extremely short timescales.”

The fact that, typically, there is a very high percentage of metal removal from the raw material is key to the solution that has been adopted by K+K.

“In this situation additional machining centres are able to increase the output without any increase in the workforce,” says Keith Pain.

A significant part of K+K’s recent investment involves two new compact vertical machining centres supplied by XYZ Machine Tools Ltd. These are installed alongside an identical XYZ Mini Mill 560 that K+K has operated for several years. During urgent batch production all three are typically machining similar components, with the cycles phased so that the operator can tend each machine in turn as required. In fact, there is often spare time during which the operator can progress jobs on one of the other, slightly less automated, mills.

The choice of two more XYZ Mini Mill 560s was not only because of the good value that made the economics viable but also the experience gained with the existing machining centre. “Our machine tools have progressed according to the needs of the work and drafting technology,” says Keith Pain. “When we started nearly all drawings were manual and most jobs were one-offs, so manual machines with digital readouts were all that was really necessary, and indeed all we could afford.

"When economic CNC machining arrived we were aware of the benefits, particularly in the case of small batch work, although we investigated several options before investing in a basic XYZ ProtoTRAK-equipped CNC/manual lathe and then a ProtoTRAK CNC/manual mill."

With ever more information arriving as CAD models, and the increase in repeat components, the Mini Mill 560 was the logical next step.

Ideally suited to the type of work and batch sizes typically undertaken by K+K, the concept behind the XYZ Mini Mill 560 is a compact VMC configuration capable of machining the widest possible range of components within the smallest possible machine footprint. A 560 mm (X) by 400 mm (Y) by 500 mm (Z) working envelope is contained within a 2000 mm (width) by 2060 mm (depth) footprint.