How to Read a Cover Glass Drawing Before Requesting a Quote

1. Start With the Overall Dimensions and Thickness

 

The first step is to confirm the basic geometry of the glass part.

Check the drawing for:

Overall length and width

Nominal glass thickness

Part shape, including rounded corners or irregular profiles

Reference dimensions and units

Drawing revision number

Any dimension marked as critical

Thickness deserves particular attention. Two cover glass parts with the same length and width may require different processing conditions if their thicknesses differ.

For example, a thin cover glass for a compact electronic device may require different handling and machining considerations from a thicker panel for an industrial touchscreen.

Do not assume that every dimension shown on a drawing has the same tolerance. If the drawing does not specify a tolerance, ask the design team to confirm the applicable requirement rather than allowing different parties to interpret it differently.

Before requesting a quote: Make sure the drawing represents the latest approved design and identify any dimensions that must not change.

 

2. Check Dimensional Tolerances, Not Just Nominal Sizes

 

A nominal dimension describes the intended size. A tolerance defines the acceptable variation around that size.

This distinction matters when cover glass must fit a housing, align with a touchscreen sensor, or match a sealing structure.

Suppose a drawing specifies a glass width of 100 mm. The supplier still needs to know the permitted dimensional variation if that requirement is not otherwise defined.

Tolerances should be reviewed for:

Overall length and width

Thickness

Hole diameters and positions

Corner radii

Distance between features

Relevant edge or profile dimensions

It is also worth checking whether the tolerances are achievable for the selected material, thickness, geometry and processing method.

Very tight tolerances may require additional process control, inspection or manufacturing time. They should be applied where the design actually needs them, rather than automatically using the tightest possible tolerance for every feature.

For an OEM project, discuss critical dimensions with the manufacturer before finalizing the drawing. This allows the engineering team to evaluate whether the proposed specifications are practical for production.

 

3. Identify Every Hole, Slot, Notch, and Cutout

 

Openings and irregular features often require more attention than the outside dimensions.

A cover glass drawing may include mounting holes, sensor windows, speaker openings, slots, or notches for mechanical alignment. Each feature should be clearly defined.

Review the following information:

Hole or slot dimensions

Feature location relative to a defined datum or reference edge

Positional tolerances where necessary

Corner radii and internal geometry

Required edge quality around the opening

Minimum spacing between openings and the glass edge

The distance between a hole and the edge of the glass can affect manufacturing feasibility and the risk of edge damage. The actual limits depend on the glass thickness, material, geometry, processing method, and required strength.

Avoid relying on a screenshot or a drawing with unclear dimensions if a properly dimensioned CAD drawing is available.

If the part contains several openings, confirm that the manufacturer is working from the same coordinate system and reference points as the design team. This is especially important when the glass must align with an LCD, touchscreen sensor, camera, or mechanical housing.

 

4. Specify the Edge Finish and Corner Treatment

 

The outside profile is only part of the edge specification. The required edge condition should also be clear.

Depending on the application, a cover glass part may require edge grinding, polishing, chamfering, or another defined edge treatment.

These terms should not be treated as interchangeable. The appropriate finish depends on the design, handling requirements, appearance, and downstream assembly process.

Your drawing or technical specification should clarify:

Whether the edges are ground, polished, chamfered, or otherwise processed

Corner radius requirements

Whether sharp edges are permitted

Any visible edge-quality requirements

Whether chips, cracks, or other edge defects are subject to defined acceptance limits

For visible consumer electronics, edge appearance may be important. For industrial equipment, dimensional fit and resistance to damage during assembly may receive greater emphasis.

Do not rely on a general note such as "smooth edges" when the edge condition is functionally important. Define the intended finish as precisely as the project requires, and agree on acceptance criteria with the supplier.

 

5. Separate the Visible Area From the Printed Area

 

Cover glass used for displays frequently includes a printed border, logo, icon, or other decorative feature.

A common source of confusion is the relationship between the glass outline, the active display area, and the printed region.

These are different features and should be identified separately.

When reviewing the drawing, check:

The active display or viewing area

The location and width of the printed border

Logo and icon positions

Color references

Areas that must remain transparent

Registration requirements between printing and the glass outline

Any restrictions on ink coverage or visible appearance

For example, a black printed border may conceal the edge of a display module. If its position or width is incorrect, the finished part may not align visually with the display, even when the glass dimensions are within tolerance.

If color consistency matters, provide an agreed color reference and define how the finished part will be evaluated. A screen image alone may not provide a reliable basis for color approval.

For designs with multiple printed colors, include separate layers or clearly distinguish the different printing regions in the drawing files.

 

6. Define the Strengthening Requirements

 

The drawing should indicate whether the cover glass requires chemical strengthening, thermal tempering, or another specified treatment.

These processes are not automatically interchangeable. Their suitability depends on the glass composition, thickness, geometry, application, and performance requirements.

If strengthened glass is required, confirm:

The intended strengthening process

Any applicable strength or performance criteria

Relevant surface compression and depth-of-layer requirements, where specified

Whether the requirements apply to the finished part

Any restrictions associated with holes, cutouts, edges, or other features

Do not assume that the word "tempered" fully describes the technical requirements for a chemically strengthened aluminosilicate glass part.

Likewise, a statement such as "high strength" does not establish a measurable acceptance criterion.

For projects with defined performance targets, the buyer and manufacturer should agree on the applicable test methods, measurement conditions, and acceptance limits before production begins.

This is particularly important for thin cover glass, complex geometries, and parts that undergo additional processing after strengthening.

 

7. Specify AR, AG, and AF Coatings Separately

 

Surface treatments should be identified according to their intended function.

Although AR, AG, and AF coatings are often discussed together, they serve different purposes.

AR (anti-reflective): Reduces surface reflection under the specified conditions.

AG (anti-glare): Changes surface reflection characteristics to reduce distracting glare.

AF (anti-fingerprint): Helps reduce fingerprint adhesion and can make surface cleaning easier.

A drawing should indicate which treatment is required and which surface or surfaces need it.

Also consider whether the project requires specific optical performance, haze, reflectance, contact-angle, abrasion-resistance, or other measurable criteria. The relevant parameters depend on the coating type and the intended application.

If a part requires multiple treatments, clarify the required combination and any appearance or performance requirements for the finished surface.

Do not assume that specifying "AR/AG/AF" alone provides enough information for a manufacturer to select the correct process.

Where necessary, provide a separate technical specification or coating schedule that supplements the mechanical drawing.

 

8. Check Whether the Drawing Defines the Finished Part

 

A manufacturing drawing should make it clear whether the stated dimensions and requirements apply before or after processing.

This is important because a cover glass component may undergo several operations, including cutting, CNC machining, edge finishing, printing, strengthening, coating, and cleaning.

Not every project uses every process, and the sequence can vary by material and design.

For example, if the final part must meet specific dimensional requirements after all processing is complete, the acceptance criteria should reflect the finished component rather than an intermediate stage.

Review these questions with your supplier:

Are the dimensions specified for the finished part?

Are any features affected by subsequent processing?

Which operations must be completed before strengthening or coating?

Are there appearance requirements that apply after cleaning and packaging?

Does the drawing identify the required finished surface?

A clear definition of the final part helps prevent disagreements about whether a component meets the original specification.

 

9. Add Inspection and Acceptance Requirements

 

A drawing tells the manufacturer what to make. Inspection requirements explain how the finished part will be evaluated.

These requirements should be appropriate to the application and the risks associated with the component.

Depending on the project, inspection may cover:

Overall dimensions and thickness

Hole positions and profile accuracy

Surface scratches, chips, and other visible defects

Printing position and color

Optical performance

Coating characteristics

Strengthening-related requirements

Packaging and handling condition

Not every project requires every inspection item. The buyer should identify critical characteristics and agree with the manufacturer on suitable measurement methods and acceptance criteria.

For visible surface defects, it is especially useful to define the inspection conditions, such as lighting, viewing distance, inspection area, and applicable defect limits. Otherwise, the supplier and buyer may reach different conclusions when evaluating the same part.

Where formal standards or customer-specific inspection procedures apply, reference the applicable document and revision rather than relying on an ambiguous note such as "inspect according to industry standards."

You can also review your supplier's approach to cover glass quality inspection when evaluating production readiness.

 

10. Prepare the Right Files Before Requesting a Quote

 

A well-prepared drawing package helps a manufacturer understand the project without repeatedly asking for missing information.

Before submitting an RFQ, prepare the following where applicable:

A dimensioned engineering drawing in PDF

A compatible CAD file, such as DXF or DWG, if available

Material and thickness requirements

Edge-finishing and corner specifications

Printing artwork and color references

Strengthening and coating requirements

Critical tolerances and inspection criteria

Estimated order quantity and expected production volume

Prototype or sample requirements

Packaging requirements, if they are project-specific

Also identify the intended application. A cover glass component for an industrial control panel may have different priorities from one designed for a handheld electronic device or a camera system.

If some specifications are not finalized, state that clearly. A manufacturer may still be able to provide a preliminary quotation based on agreed assumptions, but those assumptions should be documented.

For example, a quotation based on a standard edge finish should not be mistaken for a quotation that includes precision polishing and a defined edge-inspection requirement.

 

A Practical Pre-Quotation Checklist

 

Use this checklist before sending your cover glass drawing to a potential supplier.

 

Latest drawing revision is clearly identified.

 

Overall dimensions and thickness are specified.

 

Critical tolerances and reference datums are defined.

 

All holes, slots, cutouts, and corner radii are dimensioned.

 

Edge finishing and corner treatment are specified.

 

Active display area and printed regions are clearly identified.

 

Printing colors and artwork are supplied where needed.

 

Strengthening requirements are defined.

 

AR, AG, or AF coating requirements are identified where applicable.

 

Finished-part requirements and inspection criteria are clear.

 

Material, quantity, application, and sample requirements are provided.

Not every project needs an extensive specification package. The objective is to provide enough information for the manufacturer to evaluate the part accurately and identify unresolved engineering questions before production.

 

Frequently Asked Questions

 

Can I request a cover glass quotation with only a PDF drawing?

Yes. A dimensioned PDF may be sufficient for an initial quotation if it clearly shows the part geometry and key requirements. A CAD file can help with complex profiles, openings, and detailed machining features. If important specifications are missing, the manufacturer may need clarification before confirming the quotation.

 

Do I need to specify every tolerance on the drawing?

You should define critical tolerances and identify the applicable general tolerance system for the remaining dimensions. Avoid leaving important fit, alignment, or functional requirements open to interpretation. Your engineering team and supplier should confirm tolerances that affect manufacturability or product performance.

 

Should strengthening and coating requirements be included in the same drawing?

They can be included in the main drawing or referenced in separate technical specifications. What matters is that the requirements are unambiguous, controlled by revision, and linked to the correct part and surface.

 

Can a manufacturer suggest changes to my cover glass drawing?

A capable manufacturer can review the design for manufacturability and identify potential issues involving tolerances, edge distances, machining features, or processing requirements. Any proposed design change should be reviewed and approved by the customer's engineering team before it becomes the production specification.

 

What if my drawing is not complete yet?

You can still contact a manufacturer for an initial feasibility discussion. Provide the available dimensions, intended application, material preference, estimated quantity, and known performance requirements. Clearly mark unconfirmed details so that preliminary assumptions are not mistaken for approved specifications.

 

Final Thoughts: A Clear Drawing Is the Start of a Better OEM Project

 

A cover glass drawing does more than define the shape of a glass part. It communicates the dimensional, visual, optical, and functional requirements that the manufacturer must meet.

Before requesting a quotation, pay particular attention to critical tolerances, openings, edge finishing, printed areas, strengthening, coatings, and final inspection criteria. These details help the supplier evaluate the project and identify potential manufacturing issues before samples or production parts are made.

At Weiman Tech, we support custom cover glass projects with application-specific material selection, precision processing, printing, strengthening, and coating options, subject to the requirements and feasibility of each project.

Planning a custom cover glass project? Send us your drawing, material and thickness requirements, intended application, and estimated quantity. We can review the available specifications, clarify missing details, and discuss a suitable manufacturing approach for your OEM project.