Sales in the three months ended September 30, 2019, increased compared to the same period in 2018 primarily due to higher volumes in our beverage packaging segments and increased sales in our aerospace segment, partially offset by the pass through of lower aluminum prices, the loss of sales from our former U.S. steel food and steel aerosol business, which was divested in the third quarter of 2018, the conclusion of the South America segment’s end sales associated with the Rexam acquisition and unfavorable exchange rates for our Europe segment. Net earnings for the three months ended September 30, 2019, increased compared to the same period in 2018 primarily due to higher volumes in our beverage packaging segments and lower income tax expense, partially offset by the conclusion of our South America segment’s end sales agreement associated with the Rexam acquisition, unfavorable U.S. aluminum scrap rates, manufacturing inefficiencies experienced in our North and Central America segment and increased business consolidation costs.
Sales in the nine months ended September 30, 2019, decreased compared to the same period in 2018 primarily due to the pass through of lower aluminum prices, the loss of sales from our former U.S. steel food and steel aerosol business, the conclusion of the South America segment’s end sales associated with the Rexam acquisition and unfavorable exchange rates for our Europe segment, partially offset by higher beverage can unit volumes and higher pricing for our Europe and North and Central America segments and increased sales in the aerospace segment. Net earnings for the nine months ended September 30, 2019, increased compared to the same period in 2018 primarily due to higher beverage can unit volumes, increased sales in the aerospace segment and lower income tax expense, partially offset by the conclusion of our South America segment’s end sales agreement associated with the Rexam acquisition, unfavorable U.S. aluminum scrap rates and manufacturing inefficiencies experienced in our North and Central America segment.
Cost of Sales (Excluding Depreciation and Amortization)
Cost of sales, excluding depreciation and amortization, was $2,363 million and $7,044 million for the three and nine months ended September 30, 2019, respectively, compared to $2,362 million and $7,083 million for the same periods in 2018. These amounts represented 80 percent of consolidated net sales for the three and nine months ended September 30, 2019 and 2018.
Depreciation and Amortization
Depreciation and amortization expense was $169 million and $510 million for the three and nine months ended September 30, 2019 compared to $171 million and $529 million for the same periods in 2018. These amounts represented 6 percent of consolidated net sales for the three and nine months ended September 30, 2019 and 2018.
Selling, General and Administrative
Selling, general and administrative (SG&A) expenses were $90 million and $328 million for the three and nine months ended September 30, 2019, respectively, compared to $113 million and $352 million for the same periods in 2018. These amounts represented 3 percent and 4 percent of consolidated net sales for the three and nine months ended September 30, 2019, respectively, and 4 percent of consolidated net sales for the three and nine months ended September 30, 2018.
Business Consolidation Costs and Other Activities
Business consolidation and other activities were $133 million and $147 million for the three and nine months ended September 30, 2019, respectively, and $32 million and $131 million for the three and nine months ended September 30, 2018. These amounts represented 5 percent and 2 percent of consolidated net sales for the three and nine months ended September 30, 2019, respectively, and 1 percent for the three and nine months ended September 30, 2018. The increase for the three and nine months ended September 30, 2019, was primarily due to charges related to the sale of the China beverage packaging business and the transfer of the Argentina steel aerosol business to held for sale, partially offset by a gain on indirect taxes in Brazil.
Interest Expense
Total interest expense was $79 million and $241 million for the three and nine months ended September 30, 2019, respectively, compared to $76 million and $227 million for the same periods in 2018. Interest expense as a percentage of average monthly borrowings was 4 percent for the three and nine months ended September 30 2019 and 2018.