How to calculate the width of the spine on the cover of a bound book? Calculation formula for spine size (including adhesive layer, with reference to Sunlife adhesive layer)

The easiest thing to get stuck when doing cover design isSpine width (spine size)——It’s too small to wrap the cover and the book back is exposed; The cover is arched and the spine is bulging. The spine width of a bound book is not determined by patting the head, it is composed of the total thickness of the paper and the thickness of the adhesive layer. Below are formulas and examples that can be directly applied.

1、 First, let’s answer directly: How to calculate the width of the spine of a laminated book

Spine width ≈ total thickness of book core paper+adhesive layer thickness (double-sided)

• Total thickness of book core paper =Total number of inner pages x thickness of a single sheet of paper
• Adhesive layer thickness =The adhesive layer on both sides of the book back after gluing (reference 2083: approximately 10-12mm book core corresponds to 0.4mm, ≥ 20mm book core corresponds to 0.8-1.0mm, subject to the process card)
• ifHardcover/hard shellAnd we need to add moreTwo cover papers and cardboardThis article focuses on the thickness of wireless adhesive packaging.

2、 Step by step calculation (with examples)

Step 1: Calculate the total thickness of the paper

Different paper weights result in varying thickness per sheet (approximate value, subject to actual paper sample):-Double adhesive paper 80g ≈ 0.07mm/sheet-Double adhesive paper 100g ≈ 0.085mm/sheet-Copperplate paper 128g ≈ 0.10mm/sheet-Copperplate paper 157g ≈ 0.12mm/sheet

ExampleA double adhesive 80g inner page with 200 pages (i.e. 100 sheets, note that “pages” are double-sided and “sheets” are one sheet):

Total thickness of paper=100 sheets x 0.07mm= 7.0mm

Step 2: Apply adhesive layer thickness

According to reference 2083, the 7mm book core is close to the lower limit of the “10-12mm book core 0.4mm” range, and the adhesive layer is taken as approximately 0.5–0.6mm(Total on both sides, subject to the process card):

Spine width ≈ 7.0+0.6= 7.6mm

Step 3: Leave a margin

The spine width during design is usually wider than the calculated valueAdd 0.5-1mm more Excess, offsetting the slight changes in the compaction of the adhesive layer and paper rebound after compaction; Round back (2873), for example, takes up slightly more space and needs to be adjusted.

3、 3 common pitfalls

1. Treat ‘page’ as’ sheet ‘200 pages=100 sheets, doubling it will directly double the spine of the book, and it won’t hold on to the bread.
2. Ignore the difference in paper weightCopperplate paper is nearly twice as thick as double adhesive paper on the same page, and mixed paper types must be counted separately.
3. Forgot to add adhesive layerOnly considering the thickness of the paper, without adding glue layer, the back of the book will be exposed; The reference for adhesive layer should be based on the accompanying process card, not on memory.

4、 How to use the adhesive layer of Sunlife book and magazine adhesive

Sunlife’s hot melt adhesive for books and periodicals matches the opening time of the paper and model (about 15-20 seconds/5-10 seconds/2-7 seconds for low/medium/high, subject to the process card), corresponding to different models: copperplate paper (396/397/398), adhesive paper (292/296/295/298), flat (391), test paper (39D), graphic and textual (393/395), etc. The “glue layer thickness” in the spine calculation can be directly applied to the reference range of 2083, and then fine tuned based on our factory’s actual book pressing performance——Excessive adhesive layer is not only wasteful, but also causes bulging of the spine and affects the calculated spine width。

5、 Relationship with Sunlife’s real business

Sunlife book adhesive covers multiple paper and machine scenarios, and the recommended adhesive thickness and opening time are provided in the accompanying “Instructions/Process Card”. When calculating the spine before printing, taking the “total paper thickness+adhesive layer” together and then using the adhesive layer of the corresponding Sunlife model as a reference can reduce the need for cover rework; If the paper is special or has many pages, you can send the parameters to Sunlife for selection and adhesive layer recommendations.

Explanation: The paper thickness in this article is an approximate value, and the adhesive layer is a general reference range. The specific measurement value of the actual paper sample and Sunlife’s accompanying “Instructions/Process Card” shall prevail; Different models have different opening times and wax quantities. Please refer to the actual model technical data for selection.