CNC machining costs will always vary depending on many different factors, including the length of time required to complete the project, materials specified, as well as the type of machine used, such as 3- and 5-axis machines. CNC machining is an integral part of many industries, getting the tools and parts you need with an accuracy that is difficult to achieve. Businesses are often looking for ways to trim their budgets; reducing CNC machining costs is no exception. If you are interested in CNC machining cost reduction, you need to understand the factors that impact the cost of CNC parts — machining time, start-up costs, material costs, and more. In this webinar, we review some of the biggest factors that can affect your CNC machining costs and specific ways to help you reduce costs on your CNC machined parts. For more information on our precision CNC machined parts, visit http://www.epectec.com/cnc-machining.

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Effective Ways To Reduce Your
CNC Machining Costs
6.23.22

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Agenda
 Overview of the Biggest Factors Affecting CNC Costs
 Understanding the Dual-Sourcing Model
 The 5 Specific Ways to Reduce Costs
 What Criteria Affect Costing and Delivery
 Summary

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Metal Craft Machining
 Who is Metal Craft Machining?
– Established in 1983
– Located in Central MA
– Acquired by Epec in 2018
– 30,000 sq ft
– Significant investment in
machinists, equipment, and
software focused on increasing
machine efficiencies.

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Overview of the Biggest Factors Affecting
CNC Costs

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Part Complexity
 Reducing CNC machining costs is directly related to the time it takes to
machine the part itself – spindle time
 Part design complexity - most significant factor affecting the cost of CNC
machining
– The more complex a design is, the more time
it take will be to fabricate
– Time is money:
• The longer it takes to machine, the more it will cost

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Part Complexity
 Higher complexity designs require:
– Advanced capability CNC machines
– Increased machining time
– Multiple setups
– Increased In-process inspections
 Part features can increase cost:
– Sharp internal corners, thin walls, deep cavities, and non-standard hole sizes.
These affect cost significantly and should be avoided unless they are absolutely
necessary.
– Surface roughness and tolerancing may require multiple passes and inspections
• Use industry standards

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Materials
 Materials specified for a part are a cost driver
 Costs associated with a material to be machined
– Raw material cost – varied material prices are determined by
material availability and their physical properties
– Overall production costs - machinability of the material
 Material machinability
– Materials that are more difficult to machine, take more
time and effort to machine
 Metals are more expensive than plastics
– Raw material and machine time

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Tooling
 Tooling determines the quality,
precision, and repeatability of the
finished part
 Reduce tooling costs
 Machining time can be reduced by
creating features that can be
fabricated using standard CNC tool
sizes
 Custom tooling is costly

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Setup
 Utilize standard fixturing
– Soft jaws
– Work off sets
 Eliminate the need for custom
fixtures and work off sets
 If custom fixtures are necessary, we
design and produce in-house

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Understanding the Dual-Sourcing Model

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What is Dual Sourcing
 Low-cost offshore (outsource) CNC machining of production parts with the
support of a U.S. machine shop and engineering team
 What does that mean?
– We will outsource everything that we can
– Our facility will be used for ITAR, prototypes, and rework when needed

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Process flow

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Model
 We have several facilities in Asia
– China & India
 The Process
– CAM/engineering done in U.S.
– Right facility for every order
– We manage the transportation to
New Bedford, MA
– Inspection done in the U.S.
– Customer’s price will include all
freight and tariffs

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Quoting
 Quoting time
– 24 hours any customer questions
– 48 hours – Red Line drawing sent to
facility
– 48 hours quote returned from Asia
– 5-6 days quotes returned to
customer
 Required for quote
– Drawing and .stp file
– Quantities to quote
– EAU
– Lead time (Standard & Quick Turn)
 What could delay the quote?
– Raw Material Quote
– Surface Finish Quote
– Component Quote

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The 5 Specific Ways to Reduce Costs

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Part Complexity and DFM
 3-axis and 5-axis mills and lathes allow for complex geometries and tight
tolerances.
– The processing cost depends on the type of machine and the number of hours it
will run
 The Design for Manufacturing process (DFM) is critical in CNC machining cost
calculations
 Design complexity dictates machining time
 Reduce feature complexity without sacrificing functionality
 Design complex parts into multiple parts that can be assembled after
machining
 Eliminate multiple machine setups and special tooling

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Part Complexity and DFM
 Guidelines:
– Internal cavities and fillets
– Increase wall thickness
– Increase radius
– Thread depth
• 3:1 depth to diameter
– Tight tolerances
• Standard tolerance
• +/-0.005” on metal
• +/-0.010” on plastic

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Materials
 Application requirements dictate the material type
 Consider a less expensive or easier-to-machine material that maintains the
design requirement
 Materials that are difficult to machine
materials consume more resources:
– Tools
– Cutting fluid
– Electricity

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Materials
 Aluminum $
– Soft
– Easy to machine
– Long tool life
– 6061, 7075
 Stainless Steel $$$
– Hard
– Difficult to machine
– Short tool life
– 303, 304, 316
 Brass / Copper $$
– Hard
– Easy to machine
– Long tool life
– 360, OFHC 101
 Plastics (mechanical grades) $$
– Soft
– Easy to machine, difficult for tight
tolerance, dimensional instability
– Long tool life
– PVC, nylon, and Delrin (PEEK is the
exception but higher cost)

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Tooling and Setup
 Tooling
– CNC designs require special tools for efficient fabrication. When designing a part,
machine time can be reduced by ensuring dimensions correspond to standard CNC
tool specifications.
– Hole, thread and cavity diameters should correspond to common CNC tool
diameters.
– Maintain hole and cavity dimensions across a part - fewer tool changes mean less
machining process.
 Reduce the quantity and type of cutting tools or tool inserts required
 Non-standard hole sizes
– Reamers, more costly

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Tooling and Setup
 Machining set up and fixture costs depend largely on the complexity of the job.
 If no custom work holding fixtures are required, fixed costs will be lower.
 Likewise, custom holders of limited complexity that can be produced in-house
will generally cost less than those that require a specialized supplier.
– Machine shops use standard work holding fixtures
• Machine vises
• Lathe jaws
• Collet holders
• Tombstones

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Surface finish
 Use standard finishes
 CNC machining produces parts that
can be used as-machined: machine
finish
 Specific applications require post-
processing operations to improve
functionality and aesthetic criteria
– Heat treatment
– Grinding
– Surface Finish
• Machine finish (surface texture)
• Polish
• Bead blast
• Plating (material dependent)
– Gold, Nickel, Silver (most metals)
– Anodize, chromate (Aluminum)
– Black Oxide (steel)
– Passivate (stainless steel)
– Avoid multiple finishes

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CAD / CAM
 A programmer converts CAD files to CAM files to CNC machine language.
This expertise is costly.
 Increase part file attributes
 CAD / solid model
– Creates 3D objects using computer-aided design software
– Accurate dimensional representation of a solid part
– Automates mathematical calculations
– Quality of model
• Material
• Threads
• Finish

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CAD / CAM
 PDF / part drawing
– Adds written detail not contained in
solid model
 CAM / Programming
– More accurate model and part
drawing means reduced
programming
– Programming time equals cost

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What Design Criteria Affects Costing and Delivery

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Wall thickness
 Increase wall thickness
– Thick walls are more stable
– Risk of finish damage from material and tool deflection
– Thin walls require shallow cutting depths, adds machine time
– Thicker walls decrease machining times and lower cost
 Minimum metal wall = 0.035”
 Minimum plastic wall = 0.060”

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Internal Radii
 Increase internal radii
– CNC milling tools are cylindrical and
create corners inside a part with a
curve or radius
– Design the part with internal radii
instead of sharp corners
– Larger internal radius = larger the
milling tool = less machining time
– Internal corner radii 1/3 depth of the
cavity

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Deep Cavities / Threads
 Avoid deep cavities
– The deeper the cavity, the longer it takes to cut away the material
– Cavities greater than 4 times the diameter of the tool require specialized tooling
 Tapped holes
– Maintain thread depth at 1.5 times the diameter
of the hole
– Large – thread mill
– Small - tap

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Tight Tolerances
 Eliminate all unnecessary decimal points from your design
 Dimensions specify the level of accuracy required for your part
 Level of accuracy determines the tools used to machine the part
 More decimal places = more intricate the tool = higher the cost
– +/-0.005″ standard
– +/-0.001″ or better can be achieved – more costly

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Summary

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Summary
 Time is money
 To reduce the cost of the production of CNC parts:
– Decrease part complexity
– Specify raw material that is lower cost and less difficult to machine
– Design using off-the-shelf tooling
– Use standard tolerances and finishes
– Eliminate custom fixturing

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Our Products
Battery Packs Flex & Rigid-Flex PCBs Cable Assemblies Printed Circuit Boards
CNC Machining User Interfaces Flexible Heaters EC Fans & Motors

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Q&A
 Questions?
– Enter any questions you may have
in the control panel
– If we don’t have time to get to it, we
will reply via email

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Thank You
Check out our website at www.epectec.com.
For more information email sales@epectec.com.
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