spindle technology - toolholder characteristics

There are three major issues to think about when considering the proper toolholder for a high-precision application: (1) rigidity (2) accuracy (3) balance.

Much has been said in the industry today about the issue of balance, but it is important to consider the combination of all three of these issues when providing the best solution. This involves both of user and machine maker to set-up and maintain a proper quality of the machine, that the work result's quality might be satisfactory
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spindle technology - high-speed spindles and toolholders

When first designing a machine, it's ability must be defined carefully, so that every components are designed, or chosen according to the final requirements. Every machining purpose had its own characteristic, which will affect the whole machine design. The other certain thing is that spindles, related very close to the toolholders, which will hold significant part determining the quality of machining works

A machining job generally divided into two major direction : high-speed machining, or high force machining. Older machines are usually high-forced, given tough characteristic, bulky, stiff, highly capable of high metal removal rates, but usually slower. The newer machines lately grown toward high-speed, compensating low metal removal rates with a very fast feeding, so that the machining time would not differs much. High speed machines are generally more precise, since it is mostly used for contouring, that needed smooth surface as the result.
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design guide 01 - design for assembly

It is very important for a machine designer to consider a lot of things when building a component. Whether it's able to be processed (design for manufacture); able to assembled easily (design for assembly); and even sometimes whether our machine can be repaired easily (design for maintenance).
Manufacturing process done in the machining workshop, the assembly would be done by assembly workshop. It is very important for a design engineer to know what's happening on the process. At least little by little information we gather will certainly help a lot for the next possible project.

What does it means to use "design for assembly" consideration? It means that every part is designed and modified well to ease the assembly process. As we all know, assembly is very important process that must be done correctly in order to obtain the desired shape (and often, includes obtaining functionality too)
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weldment design 04 - product design rules

Welding may be imperfect and there's a million ways to overcome the distortion, but the best thing to do is considering the product's design carefully so that the effort on manufacturing is kept minimum
Just like plastic molding and sand casting, each welded product must be designed thoroughly according to the process they had to undergo. There is still some chance the distortion would happen, but on a straight line of procedures and a wise design, it wouldn't spend too much energy compared to a harshly designed ones.
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weldment design 03 - welding jigs

When you're talking about welding, the use of jigs, fixtures and positioners is usually desirable, for at least four reasons:
1. To minimize distortion caused by heat of welding.
2. To permit welding in a more convenient position.
3., To increase welding efficiency and productivity.
4. To minimize fit-up problems. With a welding jig or fixture, the components of a weldment can be assembled into accurate alignment and held securely in proper relationship and with correct fit-up during positioning and during welding so that all finished parts coming from the jig or fixture will be uniform.
For high quantity production, it is very economical to design and construct an accurate, durable jigs and fixtures.
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weldment design 02 - distortion

There was a time when the welding operator used to pick up his shield and electrode holder and commenced welding a job, beginning and finishing at any place. If the completed work became distorted, it was taken for granted that it could not be avoided. The impression was that all welding caused distortion, so there would be no point in worrying.
This was purely ignorance, because distortion can be controlled and minimized by approaching the job in a correct manner. Today, welded work is being completed with minimum or no distortion. For example, large machine beds are being fabricated out of rolled steel sections and plates and welded within a tolerance of 1.5 mm.

During welding, the base metal near the arc is heated to the melting point. A few centimeters away, the temperature of the base metal is substantially lower.
This sharp temperature differential causes non uniform expansion followed by base metal movement, or metal displacement if the parts being joined are restrained. Also, the expansion of the hotter base metal (i.e., which is nearer the welding arc) is subject to restraint, due to the resistance of comparatively colder metal away from the welding arc. The metal nearer the arc expands more than that away from the arc.
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weldment design 01 - welding joints

Before an arc can be struck on metal, the product must be designed to serve its purpose, the material chosen and the method of welding determined in more or less detail. The weldment design engineer must understand the principle of welding design :
1. Approach the redesign of previously cast, forged or riveted products as a new design, on the basis of the functions to be performed.
2. Use materials, where possible, which require the least in welding precautions and least skill.
3. Welding is a means to an end, but to the designer not an end in itself. Avoid extra and unnecessary joints by flanging, bending or rolling, and use of standard sections, stampings, small castings or forgings, wher ever necessary or advisable.
4. At least mentally review all the welding processes available and applicable to various parts of the design on the basis of material, thickness, form and quantity.
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tolerances - ISO tolerances

I've been working with machine for several years, and I learned that it is principally impossible to produce machine parts with absolute dimensional accuracy. In fact, it is not necessary or useful. It is quite sufficient that the actual dimension of the part is found between two limit dimensions and a permissible deviation is kept with production to ensure correct functioning of engineering products. The required level of accuracy of production of the given part is then given by the dimensional tolerance which is prescribed in the drawing. The production accuracy is prescribed with regards to the functionality of the product and to the economy of production as well.

A coupling of two parts creates a fit whose functional character is determined by differences of their dimensions before their coupling. 

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tolerances - surface finish

Mostly in design we are talking about fulfilling a component's specification. Whether it's about dimensional tolerance, shape, or maybe the desired surface finish. As we know before, surface finish and tolerance are closely linked. A component that are manufactured precisely, would have a good surface finish, on the other hand, rough surface finish usually hold a less precise dimension

The ability of a manufacturing operation to produce a specific surface roughness depends on many factors. For example, in end mill cutting, the final surface depends on the rotational speed of the end mill cutter, the velocity of the traverse, the rate of feed, the amount and type of lubrication at the point of cutting, and the mechanical properties of the piece being machined. A small change in any of the above factors can have a significant effect on the surface produced. There are 3 components defining the surface texture, that is : lay, surface roughness, & waviness

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tolerances - geometric tolerance

Geometric dimensioning and tolerancing (GD&T) is used to define the nominal (theoretically perfect) geometry of parts and assemblies, to define the allowable variation in form and possibly size of individual features, and to define the allowable variation between features. Dimensioning and tolerancing and geometric dimensioning and tolerancing specifications are used as follows:

• Dimensioning specifications define the nominal, as-modeled or as-intended geometry. One example is a basic dimension.
• Tolerancing specifications define the allowable variation for the form and possibly the size of individual features, and the allowable variation in orientation and location between features. Two examples are linear dimensions and feature control frames using a datum reference (both shown above).

There are some fundamental rules that need to be applied :

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gear technology - cycloid

The word Cycloid, with its adjective Cycloidal, is derived fromHypocycloid which describes the curve traced by a point on the circumference of a smaller circle rotating inside the circumference of a larger fixed circle

GEAR RATIO CALCULATION

The reduction rate of the cycloidal drive is obtained from the following formula, where P means the number of the ring gear pins and L is the number of pins on the cycloidal disc.

Ratio = (P - L) / L

Where P = Number of ring gear pins/rollers
             L = Number of lobes on a cycloidal disc

The method of operation is just like this :

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belt drive technology - basic belt types

A belt is a loop of flexible material used to link two or more rotating shafts mechanically. Belts may be used as a source of motion, to transmit powerefficiently, or to track relative movement. Belts are looped over pulleys. In a two pulley system, the belt can either drive the pulleys in the same direction, or the belt may be crossed, so that the direction of the shafts is opposite. As a source of motion, a conveyor belt is one application where the belt is adapted to continually carry a load between two points.

Belts are the cheapest utility for power transmission between shafts that may not be axially aligned. Power transmission is achieved by specially designed belts and pulleys. The demands on a belt drive transmission system are large and this has led to many variations on the theme. They run smoothly and with little noise, and cushion motor and bearings against load changes, albeit with less strength than gears or chains. However, improvements in belt engineering allow use of belts in systems that only formerly allowed chains or gears.
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bearing technology - rolling element bearing

A rolling-element bearing is a bearing which carries a load by placing round elements between the two pieces. The relative motion of the pieces causes the round elements to roll with very little rolling resistance and with little sliding.
Most rolling element bearings use cages to keep the balls separate. This reduces wear and friction, since it avoids the balls rubbing against each other as they roll, and precludes them from jamming
Even though some other kind of bearings are better in one or another specific attributes, many people think that it gives a pretty good tradeoff between cost, size, weight, capacity and durability. Therefore, it is one of the most widely used in machinery design
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bearing technology - plain bearing

A plain bearing, also known as a plane bearing, is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore the journal (i.e., the part of the shaft in contact with the bearing) slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe.

Plain bearings, in general, are the least expensive type of bearing. They are also compact, light weight, and have a high load-carrying capacity. Read more

gear technology - harmonic drive

A Harmonic Drive (also known as "Strain Wave Gearing") is a special type of mechanical gear system that can improve certain characteristics compared to traditional gearing systems (such as Helical Gears or Planetary Gears). Basically it uses the flexibility of metal as the main component of mechanism

The mechanism is comprised of three components:
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gear technology - epicyclic/ planetary

Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer gears, or planet gears, revolving about a central, orsun gear. Typically, the planet gears are mounted on a movable arm or carrier which itself may rotate relative to the sun gear. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes with the planet gears.

The axes of all gears are usually parallel and what's more is that the sun, planet carrier and annulus axes are usually concentric
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belt drive technology - design and usage guideline

Unlike many old machines that employs gears for transmission method, Newer machines began to grow fond using belt drive, since it's cheaper, offers safety (belts will break on overload, unlike gears that take everything down with it) , easier to apply and it's easier for maintenance. One thing that we might forgot to highlight is that the belt drive efficiency actually depends a lot in heat factor.

Lifetime and performance in timing belts are greatly affected by the type of reinforcement employed. This internal component largely determines belt strength (modulus), creep, flex fatigue, and length variability (caused by humidity and temperature variation). Even though timing belt drives are generally considered to be very efficient, the operating temperatures they are exposed to can have a significant effect. Elastomers that run well hot will generally become much stiffer at low temperatures. This reduces drive efficiency as more energy is required to bend the belt around the pulleys. Elastomers that flex at lower temperatures are available, but they often wear too quickly at mid-range and elevated temperatures.
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gear technology - basic gear types

I believe almost every machinist or engineer had dealt with gears. Gear are of the workhorses of motion control systems. They can turn RPMs into muscle for a conveyor belt moving heavy boxes or convert the torque of a wind turbine into sufficient speed to drive a generator. They can completely change the direction of motion. The technology is powerful, with sufficient options to satisfy virtually every occasion - when used properly, that is. There's so much types of gear, and each have its own advantages as well as disadvantages. Let's take a look at the basic types,  the one that is used as basic for another gear-arrangements or design modification

Gear is a mechanical device that transfers power from one element to another in a system. We define the gear ratio G for two gears as the ratio of their diameters, D1 and D2
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screw technology - ballscrew vs. leadscrew

Ballscrews and lead screws are the workhorses of today's motion-centric automation environment. In that light, making the correct choice for an application is extremely important.

Ballscrew technology allows balls to roll between the screw shaft and the nut to achieve high efficiency, usually above 90%, depending on lead angle. Its required driving torque is only one third of a conventional lead screw. As a result, ballscrews are capable of converting rotational motion to straight motion and vice versa. This screw type is suitable when smooth motion, efficiency, accuracy, and precision are a priority. The rolling elements eliminate sliding friction, so smaller motors can be used to drive ballscrews. And, because rolling motion is easier to control, accuracy and precision are also easier.

Lead screws are different in that there are no recirculating elements, and they are often used for simple transfer applications when speed, accuracy, and precision, are not as critical as rigidity and the load. On a positive note, more surface contact of the threads can make for a higher load rating of the nut over ballscrews. However, their metal-to-metal contact and high friction makes lead screws more suited to applications that do not require prolonged continuous movement or high speed.
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motor technology - IP rating

Choosing a motor for drive in a system is not a hard thing to do as long as you know the specification and the environmental requirement. It means we have to define how bad the working area surrounding the motor, as dust and water are critical for the motor's lifetime.

 The IP Code (or International Protection Rating, sometimes also interpreted as Ingress Protection Rating) consists of the letters IP followed by two digits and an optional letter. As defined ininternational standard IEC 60529:

The first digit indicates degree of protection provided by the enclosure with respect to persons and solid foreign objects entering the enclosure;
The second digit indicates degree of protection provided by the enclosure with respect to harmful water ingress.

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