Statement of Work for Custom Magnet Projects: What Buyers Should Write Before PO

Custom magnet projects rarely fail because someone forgot to specify “1 Tesla.”

They fail because important assumptions were never written down.

A buyer may expect a complete laboratory-ready system. The supplier may understand the quotation as covering only the magnet and power supply.

The customer may expect ±1% field uniformity across an entire sample volume. The supplier may have calculated uniformity only along one axis.

The buyer may assume Factory Acceptance Testing includes measured field maps. The supplier may understand FAT as basic functional testing.

None of these situations necessarily means either side is acting improperly. They usually mean the scope was not defined precisely enough before the purchase order was issued.

For custom electromagnets, Helmholtz coils, magnetic calibration systems, and integrated field-generation platforms, a well-written Statement of Work for custom magnet projects is one of the most effective ways to reduce technical misunderstandings, uncontrolled scope growth, schedule delays, and acceptance disputes.

This guide explains what buyers should define before PO—and what should remain flexible enough for the magnet supplier to engineer properly.

1. What Is a Statement of Work in a Custom Magnet Project?

A Statement of Work, or SOW, defines what the supplier is expected to provide and how successful completion will be judged.

For a custom magnetic field system, the SOW may cover:

• Required magnetic performance
• Mechanical working space
• Power supply requirements
• Cooling
• Control and communication interfaces
• Fixtures
• Measurement and calibration
• Factory testing
• Documentation
• Delivery boundaries
• Buyer and supplier responsibilities
• Acceptance criteria

The SOW does not need to become a 100-page engineering specification.

In many laboratory projects, five to fifteen well-written pages can be far more useful than a long document full of copied technical language.

The goal is clarity.

2. Specify the Required Result—not Every Design Decision

One of the biggest mistakes buyers make is trying to design the magnet themselves inside the procurement specification.

For example:

Over-specified approach:

“The magnet shall use exactly 1,250 turns of rectangular hollow copper conductor wound in six layers with a specific conductor cross-section.”

Unless there is a strong engineering reason for those exact details, that specification transfers unnecessary design responsibility to the buyer.

A better requirement is:

Performance-based approach:

“The system shall generate at least 1.0 T at a 25 mm pole gap under continuous operating conditions without exceeding the manufacturer’s specified thermal limits.”

Now the supplier remains responsible for solving the engineering problem.

This principle is also consistent with current U.S. Federal Acquisition Regulation guidance for performance work statements: requirements should, where practical, describe the required results rather than dictate how the work must be performed, while allowing performance to be assessed against measurable standards.

For custom magnet projects, this distinction is extremely important.

3. Start the SOW with the Experimental Objective

Before listing specifications, explain what the system is actually supposed to do.

Weak Project Description

“We require a 3-axis Helmholtz coil.”

Better Project Description

“The system will be used for three-axis calibration of a magnetometer over ±500 µT. The sensor assembly is approximately 180 × 120 × 100 mm and must remain stationary at the center of the coil while the magnetic field vector is controlled electronically.”

That second description immediately helps the supplier understand:

• Why three axes are required
• Approximate field magnitude
• DUT dimensions
• Calibration purpose
• Whether physical rotation may be necessary
• Required access around the DUT

Context improves engineering decisions.

A Good SOW Introduction Should Usually State

• Intended application
• DUT or sample type
• Main measurement objective
• Required operating environment
• Whether this is research, calibration, production testing, or integration into a larger system

This section does not need to contain every specification.

It explains why the specifications exist.

4. Define the Magnetic Field Requirement Correctly

“Maximum magnetic field” is rarely enough.

For an Electromagnet, Define

• Required maximum field
• Pole gap at which that field is required
• Pole diameter
• Required usable gap range
• Continuous or intermittent operation
• Required field direction
• Required field polarity
• Ramp requirements, if relevant

A requirement such as:

“1.5 T electromagnet”

is incomplete.

A more useful specification would be:

“Minimum 1.5 T at a 20 mm pole gap, measured near the magnetic center, with continuous operation if technically feasible.”

For Helmholtz Coil Systems, Define

• Field range per axis
• DC or AC operation
• Frequency range
• Simultaneous multi-axis operation
• Maximum resultant vector field
• Required homogeneous volume

For 3-axis systems, also clarify whether the field requirements apply:

• Per individual axis
• Simultaneously on all axes
• To the vector magnitude

These are not always equivalent design conditions.

5. Never Specify Uniformity Without Defining a Volume

A surprisingly common request is:

“Field uniformity better than 1%.”

That requirement is incomplete.

Uniformity must be associated with a defined spatial region.

Better Specification

“Magnetic field uniformity shall be within ±1% over a 50 × 50 × 50 mm³ central working volume.”

Or:

“Field variation shall remain within ±0.5% over a spherical volume of 30 mm diameter centered on the nominal magnetic center.”

Also Clarify

• Whether uniformity refers to magnitude only
• Whether directional error matters
• Whether specification applies to one axis or all axes
• Whether it applies across the complete operating field range

Without these definitions, two technically competent parties can interpret “1% uniformity” differently.

6. Define the DUT and Mechanical Working Envelope

A magnetic system is useless if the customer’s device cannot physically fit inside it.

The SOW should therefore include actual DUT information.

Provide

• Length
• Width
• Height
• Weight
• Mounting points
• Cable exit directions
• Connector locations

If rotation is required, include the complete rotational envelope.

The supplier should know whether space is also required for:

• Sample holders
• Cryostats
• Optical components
• Vacuum chambers
• Probe arms
• Temperature sensors
• Cameras
• Motorized stages

A CAD file or simple dimensional drawing can sometimes prevent weeks of redesign.

7. State What Is Included in the Complete System

The phrase “complete magnetic field system” is dangerous because different organizations interpret it differently.

A buyer may assume it includes everything required to operate.

A magnet manufacturer may quote only:

• Magnet
• Power supply

The SOW should explicitly define the expected system boundary.

Possible Scope Items

• Electromagnet or Helmholtz coil
• Bipolar or unipolar power supply
• Cooling chiller
• Cooling hoses
• Flow switches
• Interlock system
• Current cables
• Communication cables
• Magnetic field sensor
• Gaussmeter
• Temperature monitoring
• Fixture
• Sample holder
• Mechanical stand
• Control computer
• DAQ hardware
• Control software
• Installation accessories

Do not assume that an item is included simply because the system cannot operate without it.

Write it down.

8. Define Power Supply Requirements Separately from Magnet Requirements

The magnet and power supply are one functional system, but they have different specifications.

Power Supply Requirements May Include

• Maximum current
• Maximum voltage
• Bipolar or unipolar output
• Four-quadrant operation
• Current stability
• Current resolution
• Current ripple
• Remote programming
• Analog input
• USB
• RS-232
• RS-485
• Ethernet
• LabVIEW compatibility

The facility input power should also be stated clearly:

• 110–120 VAC
• 220–240 VAC
• Single phase
• Three phase
• 50 Hz
• 60 Hz

Do not wait until manufacturing is complete to discuss mains voltage.

9. Cooling and Duty Cycle Must Be Written into the Scope

Thermal performance directly affects magnetic field performance.

A buyer should therefore define expected operation.

Examples

• 10 minutes ON / 20 minutes OFF
• Four hours continuous
• Eight hours per working day
• Continuous 24/7 operation
• Repeated automated cycling

This helps determine whether the system requires:

• Natural air cooling
• Forced-air cooling
• Water cooling
• External chiller
• Temperature interlocks
• Flow monitoring

For high-field electromagnets, the difference between intermittent and continuous operation can significantly change magnet size, conductor design, power supply requirements, cooling architecture, and cost.

10. Define the Control Philosophy Before PO

“Computer controlled” is another specification that sounds precise but is not.

The SOW should clarify what the computer actually controls.

Possible Functions

• Magnetic field setpoint
• Coil current
• Current polarity
• Field reversal
• Ramp rate
• Multi-axis field vector
• Rotation stage
• Temperature
• Data acquisition
• Safety interlocks

Clarify the Required Interface

The buyer may need:

• Standalone front-panel operation
• PC software
• API
• Serial commands
• Ethernet commands
• LabVIEW integration
• MATLAB integration
• Python control

These requirements can change the control architecture significantly.

11. Separate “Required” from “Preferred”

This is one of the simplest ways to improve a magnet procurement document.

Do not present every desirable feature as mandatory.

Use categories such as:

Mandatory

The project cannot succeed without this requirement.

Preferred

Highly desirable, but alternative approaches may be accepted.

Optional

Should be separately quoted if available.

For example:

Mandatory:
±30 mT on each axis.

Preferred:
±50 mT if achievable without significantly increasing system size.

Optional:
Integrated 3-axis magnetic field feedback.

This gives suppliers room to propose technically sensible trade-offs.

It also prevents a useful system from being rejected because of a feature that was never actually critical.

12. Define Interfaces and Responsibility Boundaries

Custom projects often fail at interfaces rather than core components.

Examples include:

• Magnet to power supply
• Chiller to magnet
• Magnet to customer fixture
• Fixture to sample
• Software to customer’s DAQ
• Control system to laboratory PLC
• Cryostat to magnet gap

The SOW should define who is responsible for each interface.

Example

Supplier responsibility:

• Electromagnet
• Matching power supply
• Cooling system
• Interconnecting power cables
• Basic field verification

Buyer responsibility:

• Laboratory mains connection
• Final sample fixture
• Facility cooling water
• Customer DAQ integration

This simple division prevents the phrase:

“We assumed you were supplying that.”

from appearing after delivery.

13. Write the Deliverables as an Actual List

Do not write only:

“Supplier shall provide all necessary documentation.”

That is too vague.

Specify the expected documents.

Typical Custom Magnet Project Deliverables

• Equipment
• General arrangement drawing
• Final technical specification
• Electrical interface information
• Cooling interface information
• User manual
• Field-performance test data
• Calibration certificate, if applicable
• FAT report
• Packing list
• As-built parameter summary
• Software or communication command documentation
• Warranty statement

For more complex systems, additional documents may include:

• Interface Control Document
• Technical Compliance Matrix
• Detailed FAT Protocol
• Mechanical interface drawings
• Wiring diagrams
• Recommended spare-parts list

NASA’s SOW guidance similarly emphasizes identifying required deliverables clearly and expressing outputs in concise, understandable, measurable terms. It also notes that a clear, high-quality SOW helps suppliers understand requirements, prepare more accurate pricing, and reduces later changes and disputes.

That principle applies just as strongly to a custom laboratory magnet as it does to a large institutional procurement.

14. Define FAT Before Manufacturing Begins

Factory Acceptance Testing should not be invented after the machine is completed.

The SOW should identify what the supplier is expected to demonstrate before shipment.

A Typical Magnet FAT May Include

• Visual inspection
• Dimensional verification
• Electrical safety checks
• Coil resistance measurement
• Insulation verification
• Cooling system test
• Power supply functional test
• Maximum current test
• Magnetic field measurement
• Field polarity reversal
• Communication interface test
• Continuous-operation test
• Interlock verification

For a Helmholtz coil system, FAT may also include:

• X-axis field test
• Y-axis field test
• Z-axis field test
• Cross-axis verification
• Field uniformity measurement
• AC frequency verification

For an electromagnet:

• Field versus current
• Field versus pole gap
• Polarity reversal
• Thermal performance

The exact FAT should match what matters to the experiment.

15. Do Not Ask for a Field Map Unless You Define the Field Map

“Provide a field map” sounds clear until engineering begins.

A useful SOW should define:

• Measurement area or volume
• Measurement spacing
• Number of points
• Measurement axis
• Probe orientation
• Field setpoint
• Required output format

Otherwise, the supplier may provide ten points while the buyer expected several hundred.

Example

“Measure Bz over the central 100 × 100 mm plane at a 10 mm grid spacing with the system operating at 50% and 100% nominal field.”

That can be priced and executed.

“Provide detailed magnetic characterization” cannot.

16. Acceptance Criteria Must Be Measurable

A custom magnet project should answer one fundamental question before the PO:

How will both parties know that the system has passed?

Weak Acceptance Criterion

“The magnetic field shall be stable.”

Better

“After a 30-minute warm-up, magnetic field variation at the center shall remain within ±0.1% over one hour at the specified operating point.”

Weak

“The field shall be uniform.”

Better

“Field magnitude variation shall remain within ±1% over the specified 50 × 50 × 50 mm³ working volume.”

NASA engineering acquisition guidance similarly treats acceptance criteria as criteria that must be satisfied before deliverables are accepted and recommends defining them up front along with who performs the acceptance activity and how it will be performed.

If the criterion cannot reasonably be measured, it is difficult to enforce and difficult for a supplier to price.

17. Define Which Values Are Guaranteed and Which Are Typical

Datasheets frequently contain “typical” performance values.

Custom contracts should distinguish them from guaranteed performance.

Useful Terminology

Required / Guaranteed
Must be demonstrated for acceptance.

Target
Engineering objective, but not necessarily an acceptance condition.

Typical
Representative expected behavior.

Estimated
Preliminary engineering value subject to final design.

Maximum / Minimum
Hard specification boundary.

This vocabulary matters.

If every preliminary estimate becomes a guaranteed acceptance criterion, suppliers will either increase price dramatically or decline technically interesting custom work.

18. Include Calibration Requirements Explicitly

If calibration is required, define what the word means.

Questions include:

• Which parameter is calibrated?
• At what points?
• Using what instrument?
• Is traceability required?
• Is an accredited laboratory required?
• Is a simple factory measurement report sufficient?
• Does calibration apply to the gaussmeter or the complete magnetic system?

“Calibration certificate included” can mean very different things.

A manufacturer test record and an ISO/IEC 17025 accredited calibration certificate are not automatically equivalent.

If traceability is a procurement requirement, state it before quotation.

19. Define the Installation Scope

Installation is another major source of scope confusion.

Possible commercial models include:

EXW Equipment Supply

Supplier manufactures, tests, packs, and releases the equipment.

Buyer handles:

• Transport
• Customs clearance
• Site installation
• Utilities
• Final commissioning

Remote Commissioning

Supplier additionally provides:

• Online installation guidance
• Remote startup support
• Software assistance

On-Site Installation

Supplier sends engineers to site.

If on-site service is required, the SOW should define responsibility for:

• Visa
• International flights
• Hotels
• Local transport
• Site access
• Safety training
• Daily allowance
• Installation tools

These costs should not appear unexpectedly after PO.

20. Define What the Buyer Must Provide

A good SOW does not describe only supplier obligations.

Buyer dependencies matter too.

Typical Buyer-Supplied Information

• Final DUT dimensions
• Installation drawings
• Laboratory mains power
• Cooling water
• Floor loading information
• Facility interfaces
• Shipping address
• Import information
• Customer-supplied sensors
• Existing software protocol
• Integration drawings

If customer information is required before engineering can continue, the project schedule should acknowledge that dependency.

Otherwise, supplier delays and buyer delays become difficult to separate.

21. Build Technical Review Gates into Complex Projects

For a simple standard electromagnet, extensive reviews may be unnecessary.

For a complex customized magnetic field platform, engineering review milestones can reduce risk.

Possible Review Sequence

Stage 1 — Requirement Confirmation

Both sides freeze the key performance requirements.

Stage 2 — Preliminary Design Review

Review:

• General architecture
• Approximate dimensions
• Magnetic performance
• Mechanical interfaces

Stage 3 — Final Design Confirmation

Confirm major production drawings and interfaces.

Stage 4 — FAT Review

Agree on testing procedures before final production completion.

Stage 5 — Shipment Release

Buyer reviews FAT results before shipping.

This structure is especially useful when the system integrates magnets, cooling, fixtures, sensors, motion, DAQ, and custom software.

22. Add a Formal Change-Control Rule

Custom scientific equipment evolves.

That is normal.

A customer may change:

• Sample dimensions
• Required field
• Optical access
• Pole gap
• Communication interface
• Fixture design
• Delivery documentation

The problem is not change.

The problem is uncontrolled change.

The SOW should therefore define that changes affecting technical scope, cost, or schedule require written agreement.

A Simple Change Rule

“Any change to the agreed technical scope after design confirmation shall be evaluated for its impact on performance, cost, and delivery schedule before implementation.”

This protects both parties.

It also distinguishes:

Correction of non-compliance

from

new customer requirement

Those are commercially different situations.

23. Be Careful with “Equivalent or Better”

Procurement documents frequently contain phrases such as:

“Supplier may offer equivalent or better specifications.”

That can be useful, but only when equivalence can be judged objectively.

For example, a physically smaller coil is not automatically “better” if it reduces uniform volume.

A higher maximum field is not automatically better if:

• Cooling demand increases
• Noise increases
• Power requirements increase
• Working space decreases

Custom scientific equipment is a system of trade-offs.

Define the requirements that matter instead of assuming that every larger number represents improvement.

24. Do Not Turn Preliminary Quotation Data into Accidental Contract Requirements

During early technical evaluation, suppliers often provide:

• Preliminary dimensions
• Estimated weight
• Simulated field values
• Approximate cooling demand
• Concept drawings

These values may change during detailed engineering.

The final PO package should clearly identify which document controls.

Recommended Document Hierarchy

For example:

1. Final signed technical specification
2. Approved SOW
3. Supplier’s final technical proposal
4. Commercial quotation
5. Preliminary correspondence

Without a hierarchy, an old email can later conflict with the final engineering agreement.

For customized equipment, document version control matters.

25. A Practical SOW Structure for Custom Magnet Projects

Buyers do not need to reinvent the document every time.

A practical structure can look like this:

1. Project Background

Explain the experiment and intended use.

2. Scope of Supply

State exactly what equipment and services are included.

3. Magnetic Performance

Define field, gap, uniformity, stability, frequency, polarity, and operating mode.

4. Mechanical Requirements

Define DUT dimensions, working volume, fixture interfaces, and access.

5. Electrical and Power Requirements

Define mains supply, power supply behavior, communication, and interfaces.

6. Cooling and Environmental Requirements

Define cooling infrastructure, ambient conditions, and duty cycle.

7. Control and Software

Define local control, remote control, software, API, and DAQ integration.

8. Documentation

List required manuals, drawings, reports, certificates, and software documentation.

9. Factory Acceptance Test

Define measurements and test procedures.

10. Acceptance Criteria

Define pass/fail requirements.

11. Installation and Commissioning

Define supplier and buyer responsibilities.

12. Delivery and Packaging

Define destination and packaging expectations.

13. Warranty

Define warranty period and scope.

14. Project Schedule

Define major milestones.

15. Change Management

Define how post-approval changes are handled.

This structure works for projects ranging from a customized electromagnet to a multi-axis Helmholtz coil calibration platform.

26. What Buyers Should Send with the RFQ

The best time to write most of the SOW is before asking for the final quotation, not after the supplier has priced an incomplete requirement.

A strong RFQ package may contain:

• SOW
• Technical requirement table
• DUT drawing
• Installation-space drawing
• Required interfaces
• Required documentation list
• Target delivery schedule

This gives suppliers enough information to evaluate the real engineering scope.

The result is usually a quotation that is easier to compare and much less likely to require major revision later.

27. How Cryomagtech Approaches Custom Magnet Project Definition

Cryomagtech supplies magnetic field systems including:

• Electromagnet systems
• Helmholtz coil systems
• 3-axis Helmholtz coil systems
• Matching magnet power supplies
• Magnetic field measurement configurations
• Custom fixtures and integration solutions

For customized projects, we recommend defining the measurement objective and acceptance requirements first, then allowing the magnetic, thermal, mechanical, and control architecture to be engineered around those requirements.

👉 Product link placeholder: Cryomagtech Custom Electromagnet & Helmholtz Coil Systems

A useful technical discussion before PO may include:

• Target field and working volume
• DUT dimensions
• Required uniformity
• Duty cycle
• Cooling
• Fixture arrangement
• Control interface
• FAT
• Documentation
• Integration boundaries

The purpose is not to make procurement more complicated.

It is to make the project simpler once manufacturing begins.

28. The Best SOW Prevents the Wrong Argument

A strong Statement of Work does more than protect the buyer.

It protects the supplier from ambiguous expectations.

The best custom magnet projects normally have three characteristics:

• The buyer defines what the experiment genuinely requires.
• The supplier retains enough engineering freedom to design the solution.
• Both parties agree before PO on how completion will be demonstrated.

That is the real function of a Statement of Work for custom magnet projects.

It turns an informal technical discussion into an executable project.

And for custom scientific equipment, that can be just as important as the magnet specification itself.

References

U.S. Federal Acquisition Regulation — FAR 37.602 Performance Work Statement

The FAR recommends describing required results rather than prescribing the method of performance and using measurable performance standards wherever practicable. This is a useful principle when defining performance-based requirements for custom scientific equipment.

Source link: Acquisition.gov — FAR 37.602 Performance Work Statement

NASA — Guidance for Writing Work Statements

NASA’s SOW guidance explains that clear work statements improve supplier understanding and proposal quality and can reduce later change orders, delays, claims, and disputes. It also emphasizes clear performance requirements and measurable deliverables.

Source link: NASA — Guidance for Writing Work Statements

Key Takeaways

• A Statement of Work should define the required outcome, not unnecessarily dictate the supplier’s engineering design.
• Explain the experimental objective before listing technical specifications.
• Magnetic field requirements must include operating conditions such as pole gap, working volume, duty cycle, or frequency.
• Never specify field uniformity without defining the measurement volume.
• Define DUT dimensions and the complete mechanical working envelope.
• Explicitly list everything included in the system.
• Separate magnet, power supply, cooling, control, and fixture requirements.
• Define supplier and buyer responsibility boundaries.
• List required documentation rather than asking vaguely for “complete documentation.”
• Agree on Factory Acceptance Testing before manufacturing.
• Acceptance criteria should be measurable.
• Distinguish guaranteed, target, typical, and estimated values.
• Define calibration requirements precisely.
• Complex projects benefit from design-review milestones.
• Changes after technical approval should follow a written change-control process.
• The final contractual document hierarchy should be clear before PO.