Design for Manufacturing Course 8 Part 1: CNC - DragonInnovation.com

Summary

The video script delves into the intricacies of machining and stamping, highlighting the four-step process: part overview, technique pros and cons, process workings, and material considerations. It underscores the versatility of machining, with its wide material range and ability to create complex geometries without tooling. The discussion contrasts machining's precision and repeatability with its potential for long cycle times and waste from the subtractive process. Design guidelines are provided to optimize machining, emphasizing ease of production and material selection. The script also touches on various machining operations like lathe, milling, drilling, and grinding, and the importance of considering machine capabilities in part design.

Takeaways

• 😀 Machining, often referred to as CNC (Computer Numerical Control), is a process where a computer controls the cutting tool, while manual machining on a Bridgeport is more suitable for prototyping and not high-volume production.
• 🔩 Machining is ideal for creating precision parts like gears and fittings that require metal for strength, corrosion resistance, or other environmental factors.
• ✅ Advantages of machining include a wide range of machinable materials, no requirement for uniform wall thickness, the ability to create complex geometries, and no need for expensive tooling as in injection molding.
• ⏱️ Machining offers shorter lead times from design to finished part and allows for quicker design iterations and validations compared to processes that require tooling.
• 💰 The cost of machining is influenced by machine overhead and labor, with longer cycle times generally resulting in higher costs.
• ❌ Limitations of machining include long cycle times for complex geometries, difficulty in machining hollow vessels, and the subtractive nature leading to material waste.
• 🛠️ There are four main types of machines in machining: lathes (horizontal or vertical), mills (vertical or horizontal), drills, and grinders, each serving different part-making functions.
• 🔧 Design guidelines for machining include minimizing material removal, using standard components, choosing easy-to-machine materials, and considering the machine's capabilities and limitations in part design.
• 🧠 Machining requires consideration of factors like clamping and tool geometry to ensure parts are held securely and machined accurately without interference.
• 🛑 Material selection for machining spans a wide range including steel, stainless steel, aluminum, titanium, copper, and plastics, though plastics are less common due to more cost-effective production alternatives.

Q & A

What are the four different steps typically involved in machining and stamping processes?

The four different steps typically involved are: 1) Overview of typical parts, 2) Pros and cons of each technique, 3) How the process works and design guidelines, and 4) Common materials used.

What is CNC and how does it differ from manual machining?

CNC stands for Computer Numerical Control, where a computer drives the cutting tool. This is different from manual machining, which is done on a Bridgeport and is better for prototyping but not for high-volume production.

What are some examples of machine parts that might be produced through machining?

Examples include precision gears, different fittings like flanges for connecting parts, and drive components to transfer power.

What are the advantages of using machining over other techniques?

Advantages include a wide range of material options, no requirement for uniform wall thickness, ability to create complex geometries, no need for tooling like in injection molding, and the capacity for quick design changes and validation.

How does machining compare to injection molding in terms of tooling and design flexibility?

Machining does not require tooling like injection molding, which can take six to eight weeks to build and is expensive. Machining allows for quicker design changes and validation without the need for extensive tooling.

What are some downsides to machining?

Downsides include potentially long cycle times, limitations on certain geometries, and the subtractive process leading to material waste which adds to cost.

What are the four main types of machines used in machining?

The four main machines are lathes (horizontal or vertical), mills (horizontal or vertical), drills, and grinding machines.

How does the cycle time for machining compare to that of injection molding?

The cycle time for machining can be longer compared to injection molding, which is usually between 25 to 45 seconds.

What are some design guidelines to consider when creating parts for machining?

Design guidelines include minimizing material removal to save time and cost, using commercially available components when possible, choosing easy-to-machine materials, and designing parts that are easy to grip and machine without interference from the chuck or cutting head.

What materials are commonly used in machining and why might plastic not be a common choice?

Common materials include steel, stainless steel, aluminum, titanium, copper, and plastic. Plastic is not commonly machined because it can often be produced more cheaply through other methods like injection molding.

How does the aspect ratio of tools affect the machining process?

The aspect ratio of tools is critical; a depth equal to three times the diameter is a good rule of thumb. Beyond five times the diameter, the risk of tool breakage increases.

Outlines

00:00

🛠 Overview of Machining and Stamping

The speaker begins by expressing excitement about discussing machining and stamping, focusing on four key steps: an overview of typical parts, pros and cons of each technique, process workings, design guidelines, and common materials. Machining, often referred to as CNC (Computer Numeric Control), involves a computer-controlled cutting tool, while manual machining is done on a Bridgeport, suitable for prototyping but not high-volume production. Examples of machined parts include precision gears and various metal fittings. Advantages of machining include a wide range of materials, no requirement for uniform wall thickness, and the ability to create complex geometries. It also doesn't require expensive tooling like injection molding and allows for quick design validation and iteration. However, machining can have long cycle times and is not ideal for hollow vessels due to strength and cutting force limitations. It's a subtractive process, starting with a blank of material and removing it to shape the part, which can add to cost. The speaker also touches on the four main types of machines used in machining: lathes, mills, drills, and grinders.

05:01

🔩 Deep Dive into Machining Operations

This section delves deeper into the various machining operations, starting with lathe work, which is used for creating round features and involves the material spinning while the cutting tools remain stationary. The speaker explains different processes like turning, boring, threading, and parting off. The discussion then moves to milling, which is used for creating rectangular or planar parts. The operations include surfacing, edge cleaning, straddle cutting, drilling, and angled machining. The video provides a practical example of a drone component being machined, highlighting the use of an end mill for rough cuts. The absence of lubrication fluid during the process is noted, which is typically used for cooling and chip removal. The speaker also mentions the long cycle times associated with machining, especially when compared to injection molding, and how this affects part cost. The importance of precision in machining is emphasized, with tolerances playing a significant role in pricing. The summary concludes with a brief mention of the versatility of lathes in handling large parts and the efficiency of CNC-controlled machining.

10:03

🔩 Advanced Machining Techniques and Design Considerations

The third paragraph explores advanced machining techniques such as drilling, which is essential for creating holes in parts, and grinding, which is used for achieving precise thickness and surface finishes. The speaker discusses the various levels of precision that can be achieved through reaming and the use of grinding wheels. Design guidelines for machining are then outlined, emphasizing the importance of minimizing material removal to save time and cost. The use of commercially available components is encouraged over custom machining, and the selection of easily machinable materials is highlighted. The speaker advises on designing parts that can be machined in one setup to avoid the need for re-indicating and re-clamping, which adds to the cost. Aspect ratios for tooling are discussed, with a rule of thumb provided to avoid tool breakage. The importance of avoiding undercuts in design and ensuring that the chuck does not interfere with the part during machining is also mentioned. The paragraph concludes with a discussion on the variety of materials suitable for machining, with a focus on metals and the consideration of part geometry when selecting materials for machining versus other manufacturing methods like injection molding.

15:04

🔩 Multi-Axis Machining and Future Trends

In the final paragraph, the focus shifts to the trend of combining machines to perform multiple operations, such as turning and milling on the same machine. This approach, while expensive initially, can lead to cost savings by reducing the need for multiple setups and operations. The speaker also touches on the blurred lines between what constitutes a mill and a lathe, especially with the advent of multi-axis machines that can perform complex operations. The paragraph concludes with a mention of the artistry involved in machining, comparing the precision and skill required to that of an artist like Michelangelo. The discussion highlights the advanced capabilities of modern machining, including the ability to balance cutting forces and the potential for machines to perform intricate and detailed work.

Keywords

💡Machining

Machining is a process used to remove material from a workpiece to create or reveal a desired shape and size. In the context of the video, machining is often referred to as CNC (Computer Numerical Control), where a computer controls the cutting tool to achieve precision. The video discusses the advantages of machining, such as the wide range of materials that can be machined, the ability to create complex geometries, and the lack of need for uniform wall thickness, which is a constraint in injection molding.

💡CNC (Computer Numerical Control)

CNC stands for Computer Numerical Control, a technology where computers are used to control the movement of cutting tools to perform machining operations. The video highlights CNC as a method that allows for precision and repeatability in manufacturing, particularly useful for parts that require high accuracy and complex shapes that are difficult or impossible to achieve through manual machining.

💡Prototyping

Prototyping refers to the process of creating a preliminary model of a product to test and evaluate its design. The video mentions that manual machining on a Bridgeport is great for prototyping due to its flexibility, but it is not suitable for high-volume production. Prototyping is essential for iterating designs before committing to mass production.

💡Injection Molding

Injection molding is a manufacturing process for producing parts by injecting material into a mold. The video contrasts injection molding with machining, noting that injection molding requires uniform wall thickness and is not suitable for complex geometries that can be easily achieved through machining. However, it is a cost-effective method for high-volume production.

💡Material Selection

Material selection is a critical aspect of manufacturing, determining the properties and performance of the final product. The video discusses how machining allows for a wide range of materials to be used, including metals like steel, stainless steel, aluminum, and titanium, which are chosen for their strength, corrosion resistance, or ability to withstand environmental factors.

💡Geometry

In the context of the video, geometry refers to the shapes and forms that can be created through machining. The video emphasizes that machining allows for complex geometries that would be difficult or impossible to achieve through injection molding, such as undercuts, which require no uniform wall thickness.

💡Tooling

Tooling in manufacturing refers to the dies or molds used to shape materials into parts. The video points out that machining does not require tooling in the sense of large injection molds, which can be a significant cost and time investment. Machining allows for quicker design iterations and reduced costs as there is no need to create or modify expensive tools.

💡Cycle Time

Cycle time is the time it takes to complete one production cycle. The video mentions that in high-volume manufacturing, the goal is to reduce cycle time to increase production efficiency. While machining can offer design flexibility, it may have longer cycle times compared to other processes like injection molding.

💡Subtractive Manufacturing

Subtractive manufacturing is a process where material is removed from a workpiece to create a part. The video contrasts subtractive manufacturing with additive manufacturing, like 3D printing, where material is added layer by layer. Machining is a subtractive process, which can lead to waste material and higher costs compared to additive methods.

💡Design Guidelines

Design guidelines are principles and best practices used to optimize a product for manufacturing. The video discusses various design guidelines for machining, such as minimizing material removal to save time and cost, using commercially available components, and considering the ease of machining when selecting materials and part geometries.

💡Lathe

A lathe is a machine tool used to shape workpieces by cutting, boring, and turning. The video explains that lathes are used for creating round features or parts with an axis of revolution. It mentions different operations like turning, boring, and threading that can be performed on a lathe, which are essential for producing precision components.

💡Milling

Milling is a machining process that uses a rotating cutting tool to remove material from a workpiece. The video describes milling as a process typically used for making rectangular or planar parts. It explains various milling operations such as surface machining, edge cleaning, and drilling holes, which are crucial for creating parts with precise dimensions and shapes.

Highlights

Overview of machining and stamping processes, focusing on four key steps: part types, pros and cons, process workings, design guidelines, and material considerations.

Machining, often referred to as CNC, involves computer-driven cutting tools, contrasting with manual processes like those on a Bridgeport.

Examples of machined parts include precision gears and various metal fittings for strength and power transfer.

Advantages of machining include a wide range of machinable materials and the ability to create complex geometries without uniform wall thickness requirements.

Machining does not require expensive tooling like injection molding, which can take weeks to build and is costly to modify.

The process allows for quick design validation and iteration, with changes made easily in software rather than through physical alterations.

Machining is very repeatable and precise, making it ideal for parts requiring high precision.

Drawbacks of machining include potentially long cycle times, which can be a goal to minimize in high-volume manufacturing.

Limitations in what can be machined, such as one-piece hollow vessels, due to the strength of the tool and cutting forces.

Machining is a subtractive process, starting with a blank of material and removing it, which can add to cost due to material waste.

Design considerations for machining include minimizing material removal to save time and cost, and using commercially available components where possible.

Materials for machining range from steel and stainless steel to aluminum, titanium, copper, and plastics, though the latter is less common due to cheaper alternative production methods.

The lathe is used for creating round features, with operations like turning, boring, threading, and parting off.

Milling is for making rectangular parts, with operations including surface finishing, edge cleaning, straddle cutting, drilling, and angled machining.

Drilling is a fundamental operation for creating holes in parts, with various levels of precision achievable.

Grinding offers precise control over part thickness and surface finish, with options for rough and precision grinding.

Design guidelines for machining emphasize minimizing material removal, choosing easy-to-machine materials, and considering the machine's capabilities and limitations.

The discussion highlights the importance of understanding the differences between machining and other processes like injection molding for part design.

Transcripts

well thank you all for coming really

excited to talk about machining and

stamping today so wills basically

approach each process looking at these

four different steps we'll take an

overview of sort of typical parts that

you might find we'll talk about the pros

and cons of each technique look at how

the process works design guidelines and

then some of the common materials that

you might use so starting with machining

and we often call it CNC or computer

numeric control in that the computer is

actually driving the the cutting tool

the other way is just a manual process

on a Bridgeport which is great for

prototyping but it doesn't really apply

for high-volume so these are just an

example of a couple machine parts for

precision gears if you need the extra

strength of a metal gear is a good

example different fittings are flanges

connecting two parts drive components to

transfer transfer power for example so a

couple of the advantages of machining

one is you've got a really wide range of

materials like you can machine almost

anything some are obviously easier to

machine than others we would typically

in volume production think about

machining when you have to use metal so

it's either again something that you can

injection mold or something you really

need the extra strength that metal

provides or corrosion or environmental

being able to withstand with

environmental factors one of the great

things is it doesn't require uniform

wall thickness

unlike injection molding you can also

create geometry that would be very

difficult to injection mold so for

example you can do undercuts and things

like that it doesn't require tooling in

the sense meaning a big injection mold

so this is a huge constraint that's been

lifted if you're gonna build a molded

part often we'd find spend six to eight

weeks just building the tool so you can

build the part and it's very hard to

change a tool afterwards whereas with

this you can set it up you can machine

in part see how it works machine ten

parts see how that works so it's a great

way that it not only shortens your time

from design to part that you can hold in

your hand but it also makes it much

cheaper you know a tool if this is

probably vacuum-formed but if it was

injection molded a tool to do this

you're probably looking at about ten

thousand dollars for injection molding

whereas the machine it will be much much

cheaper and you can just validate the

design and make sure it works before you

before you ramp it up so that allows you

to make these changes really quickly if

you find that you have to move a hole

around or things like that it's just

changing software it's not changing

atoms and it's also very repeatable and

precise for things that require that

that precision on the downside of

machining depending on the geometry it

can have relatively long cycle times and

always the goal in high-volume

manufacturing is to get a shorter cycle

time so you can produce more of them

there are limitations on what you can

machine so it's not good for one piece

hollow vessel as we're just talking

about in the previous set of lectures

with with roto molding features exactly

just due to the strength of the tool

it's hard to there's always cutting

forces at the end of the tool so right

if you had a three with steep is a

feature by

exactly yep so you are limited from if

you were trying to drill a a deep hole

or anything like that there might be

other ways to to do it

it's a subtractive so 3d printing is

additive

this is subtractive you're starting with

the blank of material and then removing

it so that's going to all be waste which

will add to the cost and then you also

have doing your design consider clamping

because you need a way to hold that the

part and then the cutting head will have

its own geometry that can interfere if

you're not careful so those are things

you have to factor in in terms of the

machining process as we talked about

it's a subtractive process there's

basically four main machines you can

look at and we'll take a look at all of

them the lathe and it's both can be

horizontal or vertical likewise with the

mill yeah I think you can drill holes

and you can drive grind parts and

basically the way machining works is you

either fix at or the material and then

the other one will will move relative to

it cutting away parts you can do rough

cuts and finish cuts so often if you

have to remove a lot of material you do

a more aggressive rough cut to get it

and then for the finish cut just take a

very slick very thin slice to get a

really nice surface finish and make sure

that it's it's precise so that the the

bending of the tool due to the cutting

forces is minimized and really only

think of cost you know what drives the

cost

what's the overhead of the machine in

the labor so if it takes longer to build

a part then that part is in a linear

sense gonna be more expensive and then

these are just some basic tolerances so

you know ten thousand too bad

mm the price starts to go up

considerably so just breaking it down

into the main different operations lathe

is used to create round features or

anything with axis of revolution and

typically what happens is the material

finn's and cutting tools stay still and

there's all sorts of different processes

from turning to clean off the face too

boring where you drill a hole through it

you can thread it and then you can you

can part off a piece this is a giant

right here as a giant lathe so this is a

chuck right here and that whole part

would spin so you can make some really

massive parts so here we're just

cleaning off the face and then we're

turning down the diameter so this is a

single point cutting tool and then it's

hard to see but the material is actually

spinning

so you can see relative to

injection-molding where the cycle time

is usually anywhere from 25 to 45

seconds it's a fairly long cycle time if

you want to want to build complex parts

do you know what they're making there

this one I believe is just a demo of

that other of the machine you can see

it'd be a very hard part to a die cast

due to that you know the different wall

thicknesses and be very difficult to get

that to cool or to have their precision

and you'd also in die casting have a

parting line where this will be smooth

all the way around so that's a just a

straightforward example of turning and

it's obviously under computer numeric

control or CNC so milling is a process

typically you'll use to make rectangular

planar parts where lathe they're turning

you'll make round parts and typically

that as most people are most mechanical

engineers are trained under Bridgeport

which is a vertical turret mill there's

always also horizontal mills and your

basic operations are you can surface a

part to make it flat you can clean the

edges you can do a straddle cut which is

we'd have two cutting edges if you

wanted to control the width of a certain

part drill holes and then machine things

with an angle in it and this is a that

was pretty cool it's machining a drone

cooperate so this is not a this isn't a

part for sale this is potentially a tool

to uh to make a injection mold for a

drone you can see the material is

clamped here and then this is an end

mill that's doing some rough cuts to

clean out the are basically like

Michelangelo to release the mold from

from the block

so that's uh that's how milling works

how come there's no lubrication fluid

being sprayed on that yeah typically

you're right there would be for to

lubricate and also to cooling to get rid

of the chips

yep you often see that in fact often

there's such a great flow of it that you

can't even see the part being cut you

just see a big fire hose let's see the

next process is drilling which is

basically just to put a hole in any sort

of part and there's different levels of

precision you can get if you want a

really clean surface finished thing

you'll end up reaming it afterwards with

either a straight flute or a spiral

flute and then the last one we'll talk

about here is grinding alright and so in

this case these are parts being held on

a magnetic Chuck spinning in and this is

a grinding wheel here and you can very

carefully control the thickness or the

precision of whatever part you're you're

grinding and there's also different

levels you can do grind it down rough

and then at the very end just put a

great surface vision finish on it with

that precision grinding so in terms of

design guidelines as you think about

machining or designing parts for

machining what you want to do is

appreciate the part as much as you can

just remembering time is money so the

more you have to hog away the more

expensive it is the longer it takes it

also reduces the overall costs if you

can use commercially off-the-shelf

components rather than having to machine

your own chances are they're built in a

much higher volume and you can put them

in so if you have a precision screw or

things like that it's obviously much

easier to buy it then the machining your

own you want to pick materials that are

easy to machine so make life easy for

the factory if possible use only one

machine sometimes if you're designing

something or a more efficient design

would be have the ability to say

there are Miller a lathe to be able to

do all the features it gets more

expensive if you have to take it from a

mill say and then put it on a lathe

because you have to re indicate it to

get everything true and then clean it

and again time is money so that would be

a more expensive part likewise you want

to avoid having to recheck it or turn it

over to grab different parts to be able

to machine the underside typically

external diameter should get bigger just

so that you don't need a tool with an

undercut on it and in the same way

internal diameter should get smaller as

you go down and then as Andrew is

talking about you want to be conscious

of just the aspect ratio of your tools

so a great rule of thumb is you know a

depth equal to three times the diameters

okay after you get to five times your

you're stretching it and there's a good

chance of breaking the tool and then as

you're machining it you want to make

sure that the Chuck doesn't actually

interfere or bump into your part because

that creates a giant nightmare and that

you can imagine if your machine is a a

piece of sheet metal that may be very

difficult to hold depending on how you

look at it so you do want to design

parts that are easy to grip and then

this one is kind of obvious but you

can't drill a curved hole you probably

approach it a few different ways you may

drill a few holes and then another one

and put a plug in it whereas in 3d

printing it's easy so that's one of the

areas sometimes we see people get into

trouble is that you can 3d print

anything you can design but just because

you can 3d print it doesn't mean you can

machine it and you have to be careful of

the two in terms of the materials

there's a huge array of materials that

you can pick from from steel stainless

steel aluminum titanium copper plastic

we typically in production wouldn't

machine plastic because you could

probably produce it other ways that are

that are cheaper it's used a lot for

plastic

dick yes right so it sounds like in that

case it'd be a uniform wall thickness

issue or the geometry was such that you

didn't want to have to shell it out

exactly so a good thought exercise would

be if you had a part how would the

design look if you were to machine it

versus injection molded typically

injection molding there would be massive

coring but if for machining that's the

last thing you wanted to just because it

adds so much time and money it actually

might be a fun exercise at some stage

just look at the same part through two

different lenses so anyhow that's the

machining or CNC any any questions on

that I would just want one common

applicator CNC would be the post for

both machining of cast organs absolutely

yes so for a casting it's typically

gonna have a very rough like a sand

casting will have a rough surface finish

and you'll want to go and touch it for

any areas that require a precision and

that's a great point Bob and in doing

that it does add to the cost of it that

it's one extra operation you got to

figure out how to get it on the machine

tool get it indicated and so on so yeah

every time you touch something yeah you

had money there's also a huge push

amongst machine manufacturers do combine

machines build turns and multi axes yes

and they're very expensive up front but

if you design your partner really it

means you don't have to touch it very

much and they can actually be quite

cheap yeah I was as I was looking for

some of the video here that the line

between what's a mil and what's a lathe

bores like know where to put this stuff

yeah borrow dollars it's crazy like

you've got the lathe going but then

there's spinning cutting head sense yeah

I had one I didn't end up including but

it was machining it might have been in

like a Lamborghini crankshaft just

watching everything dance a lot of times

I'll have two tools they can balance the

cutting forces very cool yeah it since

it's like an artist screaming this thing

I mean it's just it's insane