cutting tool technology - tool geometry

Every machinists use cutting tools to make up a desired shape in a desired dimension, most of us are limited only on using it, but a little study will help to find the best method and tool to work on certain workpiece.
Most of these considerations involve cutting tool geometry :

• Lead angle is the approach angle of the cutting edge as it enters the workpiece. The lead angle controls the direction of the radial cutting force and axial cutting force.
• Rake angle is the incline of the top surface of the cutting edge that makes contact with the chip. The rake controls the degree of cutting forces and cutting edge strength.
• Clearance angle is the angled relief behind the cutting edge that eliminates interference between the cutting tool and the workpiece.
• Cutter diameter is the maximum flat surface a cutter will machine.
• Insert pitch is the distance between corresponding positions on one insert to the same position on the subsequent insert.
• Insert density is the number of inserts, or cutting edges, per inch of diameter.
• Hand of cut determines the cutter rotation direction. Milling cutters are designed to cut clockwise or counterclockwise.
• Mounting adaptation is determine by the type of machine spindle on which the rotating cutter is mounted. The method of mounting is a major factor in determining the rigidity and performance capability of the cutter.

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solidworks - viewing mates

I believe every 3d software user had at least several experience with assembly. It's easy to create, but sometimes it will take a significantly long time just to edit, when you decide to change the assembly structure, or when one of the component need to be replaced. The main cause is not in editing, but in finding the exact mate between two components that we need to edit. It might as well become a long painful journey for your tired eyes.

There are several possible solution for this,
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solidworks - delete

Most people know that you can delete lines from a sketch, or features from the Solidworks feature Manager, by pre-electing the object(s) and then simply hitting the DELETE key. But only few had known that over the last 4 years, the programmers have enhanced the intelligence behind the DELETE key, allowing it to react differently according to situations we're in.

Here's how DELETE will act when faced on several different circumstances :
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solidworks - using derived sketch

Derived sketch is one of a good feature that often overlooked. This tool derives a sketch from another sketch that belongs to the same part, or derives a sketch from another sketch in the same assembly! When you derive a sketch from an existing sketch, you are assured that the two sketches will retain the characteristics that they share in common. Every changes that you make to the original sketch are reflected in the derived sketch. Here I will show how to derive a sketch from a sketch in the same part:
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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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Failure Mode & Effects Analysis [FMEA]

FMEA is a procedure in product development and operations management for analysis of potential failure modes within a system for classification by the severity and likelihood of the failures. A successful FMEA activity helps a team to identify potential failure modes based on past experience with similar products or processes, enabling the team to design those failures out of the system with the minimum of effort and resource expenditure, thereby reducing development time and costs. It is widely used in manufacturing industries in various phases of the product life cycle and is now increasingly finding use in the service industry. Failure modes are any errors or defects in a process, design, or item, especially those that affect the customer, and can be potential or actual. Effects analysis refers to studying the consequences of those failures.
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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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